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Engine Starved for Gas
#1
C
Chartman
C
Chartman
I need help diagnosing a problem with a Poulan lawn tractor that I bought used last summer:
Poulan Pro 300EX; 42 inch cut; Product Model 960420088; Maintenance Level 00; Model: PB18542LT; Serial Number: 020209D002294
Briggs and Stratton Engine; 18.5 Hp; Model: 31C707; Type 0603 B2; Code: 090904ZA
It starts and runs fine for about 20 minutes. Then it starts to sputter, as if the engine is starved for gas, on one pass. It will recover a bit on the return pass. My front lawn has, what I would describe as, a slope that may be significant. The problem gets progressively worse, and the engine will stall shortly after that without intervention.
When the sputtering problem appears, I can disengage the lower drive, (required to) lift the hood and observe the clear in-line fuel filter. It will be about empty of fuel. I can open the fuel tank cap and I observe that the filter will rapidly fill with fuel and the engine recovers.
It appears to be a simple case of lack of venting by the fuel tank cap is preventing fuel flow.
I tried the “dump test” to see if the cap allows air in the tank as fuel flowed out the open tube at the bottom. The cap passed the test. Even so, it seemed too coincidental that the fuel filter filled up when I unscrewed the gas cap, so I bought a new cap. I was not too surprised when the problem persisted today, even with the new cap.
It occurred to me that I didn’t know if this is a “hot running engine” problem or a “fuel tank half full” problem; as these conditions seem to occur simultaneously.
Today I got through almost all of the front lawn when the problem became extreme. I could see the fuel filter was pretty much empty when the engine was about to stall, but with the lower unit disengaged and the engine idling, it would suddenly fill up rapidly; even with the cap on tight. I don’t know what caused that change.
I stopped the engine and emptied the grass, then decided to fill the tank (about half full at the time) completely to the top.
I then went on to mow the back lawn, which has a steeper incline than the front, and had no problem for about 20 minutes. It did start to sputter at one point, but I was almost done and it recovered on its own. The tank was about 85% full.
The engine sounds great while it is running, but perhaps there is a vacuum leak to the gas tank?
Perhaps a cylinder head gasket leak?
I am very sure this is a “starved for gas” problem, but other than that, I’m pretty much stumped!
Help!?
Poulan Pro 300EX; 42 inch cut; Product Model 960420088; Maintenance Level 00; Model: PB18542LT; Serial Number: 020209D002294
Briggs and Stratton Engine; 18.5 Hp; Model: 31C707; Type 0603 B2; Code: 090904ZA
It starts and runs fine for about 20 minutes. Then it starts to sputter, as if the engine is starved for gas, on one pass. It will recover a bit on the return pass. My front lawn has, what I would describe as, a slope that may be significant. The problem gets progressively worse, and the engine will stall shortly after that without intervention.
When the sputtering problem appears, I can disengage the lower drive, (required to) lift the hood and observe the clear in-line fuel filter. It will be about empty of fuel. I can open the fuel tank cap and I observe that the filter will rapidly fill with fuel and the engine recovers.
It appears to be a simple case of lack of venting by the fuel tank cap is preventing fuel flow.
I tried the “dump test” to see if the cap allows air in the tank as fuel flowed out the open tube at the bottom. The cap passed the test. Even so, it seemed too coincidental that the fuel filter filled up when I unscrewed the gas cap, so I bought a new cap. I was not too surprised when the problem persisted today, even with the new cap.
It occurred to me that I didn’t know if this is a “hot running engine” problem or a “fuel tank half full” problem; as these conditions seem to occur simultaneously.
Today I got through almost all of the front lawn when the problem became extreme. I could see the fuel filter was pretty much empty when the engine was about to stall, but with the lower unit disengaged and the engine idling, it would suddenly fill up rapidly; even with the cap on tight. I don’t know what caused that change.
I stopped the engine and emptied the grass, then decided to fill the tank (about half full at the time) completely to the top.
I then went on to mow the back lawn, which has a steeper incline than the front, and had no problem for about 20 minutes. It did start to sputter at one point, but I was almost done and it recovered on its own. The tank was about 85% full.
The engine sounds great while it is running, but perhaps there is a vacuum leak to the gas tank?
Perhaps a cylinder head gasket leak?
I am very sure this is a “starved for gas” problem, but other than that, I’m pretty much stumped!
Help!?
#2
B
bertsmobile1
B
bertsmobile1
In order for fuel to get out of the tank. air has to get in.
That air will be dusty.
Add some grass clippings and you get a plug that forms in the fuel outlet of the tank.
When the tank is full you have a bigger pressure head to force the fuel through the blockage.
IF it is a Cal spec mower there will be a filtered air vent into the tank that can get blocked.
Try pulling the fuel line off at the pump and blowing back through it ( gas cap removed ) when the spluttering starts.
If it goes away for a few minutes , time to clean out the fuel tank.
If there is black debris in the fuel filter then change the fuel lines as well.
That air will be dusty.
Add some grass clippings and you get a plug that forms in the fuel outlet of the tank.
When the tank is full you have a bigger pressure head to force the fuel through the blockage.
IF it is a Cal spec mower there will be a filtered air vent into the tank that can get blocked.
Try pulling the fuel line off at the pump and blowing back through it ( gas cap removed ) when the spluttering starts.
If it goes away for a few minutes , time to clean out the fuel tank.
If there is black debris in the fuel filter then change the fuel lines as well.
#3
C
Chartman
I REALLY appreciate your input, bertsmobile1.
This machine was most likely purchased in NY or somewhere in the northeast. I saw no evidence of a fuel tank filtered air vent; just an ordinary fuel tank cap.
I don't think there is a fuel pump either. The fuel flows:
Bottom of tank -> in-line shutoff valve -> fuel filter -> plastic elbow on carburetor above the cup.
There is a solenoid shutoff on the bottom of the carb cup, that I think prevents back-fire when the engine is shuts down; but I don't see how this could be the problem.
Based on your suggestions, I think I will empty and clean all of the fuel lines, valve openings and exit port on the bottom of the fuel tank.
I probably won't mow again until next week, so we'll see if it helps at that time.
SL
C
Chartman
In order for fuel to get out of the tank. air has to get in.
That air will be dusty.
Add some grass clippings and you get a plug that forms in the fuel outlet of the tank.
When the tank is full you have a bigger pressure head to force the fuel through the blockage.
IF it is a Cal spec mower there will be a filtered air vent into the tank that can get blocked.
Try pulling the fuel line off at the pump and blowing back through it ( gas cap removed ) when the spluttering starts.
If it goes away for a few minutes , time to clean out the fuel tank.
If there is black debris in the fuel filter then change the fuel lines as well.
I REALLY appreciate your input, bertsmobile1.
This machine was most likely purchased in NY or somewhere in the northeast. I saw no evidence of a fuel tank filtered air vent; just an ordinary fuel tank cap.
I don't think there is a fuel pump either. The fuel flows:
Bottom of tank -> in-line shutoff valve -> fuel filter -> plastic elbow on carburetor above the cup.
There is a solenoid shutoff on the bottom of the carb cup, that I think prevents back-fire when the engine is shuts down; but I don't see how this could be the problem.
Based on your suggestions, I think I will empty and clean all of the fuel lines, valve openings and exit port on the bottom of the fuel tank.
I probably won't mow again until next week, so we'll see if it helps at that time.
SL
#4
B
bertsmobile1
A gravity tank will be an easier cleaning.
B
bertsmobile1
I REALLY appreciate your input, bertsmobile1.
This machine was most likely purchased in NY or somewhere in the northeast. I saw no evidence of a fuel tank filtered air vent; just an ordinary fuel tank cap.
I don't think there is a fuel pump either. The fuel flows:
Bottom of tank -> in-line shutoff valve -> fuel filter -> plastic elbow on carburetor above the cup.
There is a solenoid shutoff on the bottom of the carb cup, that I think prevents back-fire when the engine is shuts down; but I don't see how this could be the problem.
Based on your suggestions, I think I will empty and clean all of the fuel lines, valve openings and exit port on the bottom of the fuel tank.
I probably won't mow again until next week, so we'll see if it helps at that time.
SL
A gravity tank will be an easier cleaning.
#5
C
Chartman
C
Chartman
Okay; So today I pulled the fuel line from the carburetor and put the end in an empty container. I opened the fuel valve and let the fuel drain from the mostly full fuel tank with the fuel cap firmly in place. It drained out with no problem.
I removed the tank/shutoff valve/in-line filter/hoses assembly.
I cleaned everything thoroughly; inside and out. I blew out all of the passageways with compressed air.
The shutoff valve is a straight in-line device. I thought I should be able to see straight through it when the knob is in the “open” position. I could not; nor could I pass a wire through it. I could blow through it in the open position and not in the closed position. I was surprised that it had a flow direction imprinted on it. I decided to replace it.
I checked the Parts Manual that I downloaded from Briggs and got the fuel filter part number (691035) to replace that, too.
At Ace hardware I found the same Briggs shutoff valve (only “new”) in a blister pack with the knob in the “off” position; so I could not tell if it would be a clear shot through when it is in the “on” position. I prevailed on the clerk to open it, so we could check. It turns out that it is NOT a clear through passage, even in the full on position. I found another shutoff valve (at 50% higher price) that DID have a clear shot through in the open position, so I decided to buy that. I also bought a new Briggs fuel filter with the exact replacement part number I found in the Parts Manual. I was about to open it and install it when I read the package carefully. It clearly identifies this filter as “Fits engines with fuel pumps”. I have no fuel pump. This filter is a lot smaller than the one on the engine. I decided that it may not be free flowing enough for a gravity feed engine, so I stuck with the original fuel filter, which seemed easy enough to blow through.
After reassembling everything, I filled the fuel tank almost to the cap and started up the engine. It started immediately, as always.
I completed the front yard with no problems and went straight on to the back without stopping.
About half way through, the same fuel starvation problem began. The engine sputtered every time the slope of the terrain tilted the fuel away from the engine. Disengaging the lower unit and loosening the gas cap would help the engine recover. I could see the gas flow into the clear fuel filter as the engine recovered. The tank was down maybe only a quarter of a tank (or less). There was plenty of fuel in the tank and the fuel level was well above the carburetor inlet. It was a struggle to complete the mowing. I think it would have worked to fill the tank to the top again; but this ain’t right!
I am running out of ideas for what to try next. I might just eliminate the fuel filter and see how it runs. I am thinking that the problem may actually be down stream of the tank, valve, filter, hoses system. Perhaps the engine is not providing sufficient vacuum to pull in the gas it needs when hot? Poor valve seating or piston rings? Could there be “back pressure” from somewhere in the engine that keeps the fuel from flowing out of the tank?
Anyone have any ideas?
I removed the tank/shutoff valve/in-line filter/hoses assembly.
I cleaned everything thoroughly; inside and out. I blew out all of the passageways with compressed air.
The shutoff valve is a straight in-line device. I thought I should be able to see straight through it when the knob is in the “open” position. I could not; nor could I pass a wire through it. I could blow through it in the open position and not in the closed position. I was surprised that it had a flow direction imprinted on it. I decided to replace it.
I checked the Parts Manual that I downloaded from Briggs and got the fuel filter part number (691035) to replace that, too.
At Ace hardware I found the same Briggs shutoff valve (only “new”) in a blister pack with the knob in the “off” position; so I could not tell if it would be a clear shot through when it is in the “on” position. I prevailed on the clerk to open it, so we could check. It turns out that it is NOT a clear through passage, even in the full on position. I found another shutoff valve (at 50% higher price) that DID have a clear shot through in the open position, so I decided to buy that. I also bought a new Briggs fuel filter with the exact replacement part number I found in the Parts Manual. I was about to open it and install it when I read the package carefully. It clearly identifies this filter as “Fits engines with fuel pumps”. I have no fuel pump. This filter is a lot smaller than the one on the engine. I decided that it may not be free flowing enough for a gravity feed engine, so I stuck with the original fuel filter, which seemed easy enough to blow through.
After reassembling everything, I filled the fuel tank almost to the cap and started up the engine. It started immediately, as always.
I completed the front yard with no problems and went straight on to the back without stopping.
About half way through, the same fuel starvation problem began. The engine sputtered every time the slope of the terrain tilted the fuel away from the engine. Disengaging the lower unit and loosening the gas cap would help the engine recover. I could see the gas flow into the clear fuel filter as the engine recovered. The tank was down maybe only a quarter of a tank (or less). There was plenty of fuel in the tank and the fuel level was well above the carburetor inlet. It was a struggle to complete the mowing. I think it would have worked to fill the tank to the top again; but this ain’t right!
I am running out of ideas for what to try next. I might just eliminate the fuel filter and see how it runs. I am thinking that the problem may actually be down stream of the tank, valve, filter, hoses system. Perhaps the engine is not providing sufficient vacuum to pull in the gas it needs when hot? Poor valve seating or piston rings? Could there be “back pressure” from somewhere in the engine that keeps the fuel from flowing out of the tank?
Anyone have any ideas?
#6
I
ILENGINE
I
ILENGINE
First order of business, I ran the 691035 filter on gravity flow engines for years without issues, so don't worry about the fuel pump rating. I went back to the 394358S filter after 2012 because it was causing issues with the filtration level not allowing enough flow with the new run under slight tank vacuum EPA vent on the tank.
You said the slope may be significant in your yard. Do you have any way to measure the slope. I am wondering, and this is just a wild though. The angle is causing the fuel to run to one side of the fuel bowl causing it to have a high enough level to burn the fuel out of the carb enough to get the main jet out of the fuel in the carb.
The other thought is the opposite of fuel starvation, and the slope is causing the fuel bowl vent to get flooded with fuel causing a rich run issue.
Just throwing some random thoughts out there for consideration.
You said the slope may be significant in your yard. Do you have any way to measure the slope. I am wondering, and this is just a wild though. The angle is causing the fuel to run to one side of the fuel bowl causing it to have a high enough level to burn the fuel out of the carb enough to get the main jet out of the fuel in the carb.
The other thought is the opposite of fuel starvation, and the slope is causing the fuel bowl vent to get flooded with fuel causing a rich run issue.
Just throwing some random thoughts out there for consideration.
#7
B
bertsmobile1
B
bertsmobile1
If it works every time from full to 3/4 then it is definately a fuel supply problem.
The pressure head is not enough to unseat the float needle.
Is this the same carb that the mower came with.
Fuel pumps run about 3 to 7 psi which while not much, is more than the pressure from a gravity head.
Gravity feeds use coarser filters than pressure fed ones.
Have a close look at the needle in the float and the seat.
Chances it is sticking a little.
The pressure head is not enough to unseat the float needle.
Is this the same carb that the mower came with.
Fuel pumps run about 3 to 7 psi which while not much, is more than the pressure from a gravity head.
Gravity feeds use coarser filters than pressure fed ones.
Have a close look at the needle in the float and the seat.
Chances it is sticking a little.
#8
Boudreaux In Eunice La.
Boudreaux In Eunice La.
Ok in between my wife talking to me and trying to read all these post's...... I will comment .....
I agree with IL Engine about the filters...... I use the 691035 filters all the time on regular 8 HP Briggs and Techs the same size ......
The 691035 is a 40 Micron filter which is smaller than the 394358S filter which is 75 Microns. Not smaller in size, but smaller in the fact that it catches smaller particles of debris........
The 394358S is a small white filter and the other is a clear see thru filter.......And much bigger......
I did see see where you blew thru all the passages and then let the fuel flow from the tank into a container with no issue........
BUT even with NO fuel pump no matter what filter you have on there, the engine still works the same way with or without a fuel pump.... The engine sucks air into the carb via the intake stroke on a regular gravity feed tank..... With a fuel pump the engines are bigger and usually have bigger carbs and fuel usage / consumption.... So there is 2 ways to get more fuel to the carb and the piston / pistons.......
The only thing I can suggest is that your fuel lines are [flapping] on the inside...... Ethanol has took it's toll on them, and it don't take long... 1 month or 2 years ????
Even though you did empty the tank in a jar without the cap on or off doesn't mean anything.......... The fuel system is still under pressure with the carb doing it's normal work..... Even without the pump like I said earlier....
You got me curious though on not a see thru shut off valve ..... I have some in stock 698183 and bust a pack open and check that out and reply in a lil while ...........
Let us know Mon Ami ~!~!
I agree with IL Engine about the filters...... I use the 691035 filters all the time on regular 8 HP Briggs and Techs the same size ......
The 691035 is a 40 Micron filter which is smaller than the 394358S filter which is 75 Microns. Not smaller in size, but smaller in the fact that it catches smaller particles of debris........
The 394358S is a small white filter and the other is a clear see thru filter.......And much bigger......
I did see see where you blew thru all the passages and then let the fuel flow from the tank into a container with no issue........
BUT even with NO fuel pump no matter what filter you have on there, the engine still works the same way with or without a fuel pump.... The engine sucks air into the carb via the intake stroke on a regular gravity feed tank..... With a fuel pump the engines are bigger and usually have bigger carbs and fuel usage / consumption.... So there is 2 ways to get more fuel to the carb and the piston / pistons.......
The only thing I can suggest is that your fuel lines are [flapping] on the inside...... Ethanol has took it's toll on them, and it don't take long... 1 month or 2 years ????
Even though you did empty the tank in a jar without the cap on or off doesn't mean anything.......... The fuel system is still under pressure with the carb doing it's normal work..... Even without the pump like I said earlier....
You got me curious though on not a see thru shut off valve ..... I have some in stock 698183 and bust a pack open and check that out and reply in a lil while ...........
Let us know Mon Ami ~!~!
#9
J
jp1961
J
jp1961
Hmmm,,,the "significant slope" statement would lead me to suspect debris in the tank sloshing around in the tank and occasionally blocking the fuel supply.
Regards
Jeff
Regards
Jeff
#10
Boobala
Boobala
I have the same problem with my mower at times, only when mowing the slopes in my yard, I'm sure it's the carburetor float so I just get on the other side of the slope for a few seconds, now I mow up & down the slopes sideways up one and like a "snake" to the other side ( like mowing an "S" pattern ) as far as the filter goes it's normal for the amount of fuel in it to change (unless it's blocked of course) it seems your issue is on the slope, as you stated doing front yard, it was functioning OK I have the same engine 31c707 series but a 17.5 HP.
I completed the front yard with no problems and went straight on to the back without stopping.
About half way through, the same fuel starvation problem began. The engine sputtered every time the slope of the terrain tilted the fuel away from the engine.
I completed the front yard with no problems and went straight on to the back without stopping.
About half way through, the same fuel starvation problem began. The engine sputtered every time the slope of the terrain tilted the fuel away from the engine.
#11
C
Chartman
New "first order of business" is Thank you so much for taking the time to lend your expertise and insight.
So, if I understand you correctly, the 691035 fuel filter will probably work fine in my machine, but the real factory spec filter is 394358S? I will probably return the former and exchange it for the latter.
I went out a few minutes ago and used a couple of carpenter's levels, tape measure and some trigonometry to come up with an approximation of the slope of the backyard at its steepest pitch. I got about 12 degrees. Most of the yard is probably half that down to about level.
I am skeptical about the fuel flooding for a couple of reasons. First, the engine sputtering subsides when I see the fuel enter the empty filter. Also, the sputtering begins when the slope of the terrain tilts the fuel tank away from the engine.
As I say; I'm skeptical, but I am not ready to discard completely any reasonable possibility.
Chartman
C
Chartman
First order of business, I ran the 691035 filter on gravity flow engines for years without issues, so don't worry about the fuel pump rating. I went back to the 394358S filter after 2012 because it was causing issues with the filtration level not allowing enough flow with the new run under slight tank vacuum EPA vent on the tank.
You said the slope may be significant in your yard. Do you have any way to measure the slope. I am wondering, and this is just a wild though. The angle is causing the fuel to run to one side of the fuel bowl causing it to have a high enough level to burn the fuel out of the carb enough to get the main jet out of the fuel in the carb.
The other thought is the opposite of fuel starvation, and the slope is causing the fuel bowl vent to get flooded with fuel causing a rich run issue.
Just throwing some random thoughts out there for consideration.
New "first order of business" is Thank you so much for taking the time to lend your expertise and insight.
So, if I understand you correctly, the 691035 fuel filter will probably work fine in my machine, but the real factory spec filter is 394358S? I will probably return the former and exchange it for the latter.
I went out a few minutes ago and used a couple of carpenter's levels, tape measure and some trigonometry to come up with an approximation of the slope of the backyard at its steepest pitch. I got about 12 degrees. Most of the yard is probably half that down to about level.
I am skeptical about the fuel flooding for a couple of reasons. First, the engine sputtering subsides when I see the fuel enter the empty filter. Also, the sputtering begins when the slope of the terrain tilts the fuel tank away from the engine.
As I say; I'm skeptical, but I am not ready to discard completely any reasonable possibility.
Chartman
#12
C
Chartman
Hi bertsmobile1. Thanks again for working with me on this problem.
I bought this lawn tractor used last year. There is nothing I see that suggests to me that the carburetor has been replaced, or even tampered with; but I cannot say for sure.
I think your suggestion of a sticky float needle is a good one. I haven't had the pleasure of disassembling the carb on this unit so far, but it seems like it might be in my near future.
I think it may be possible to get at those parts without removing the whole carb. It probably should not be done over the grass.
I will get the proper fuel filter as suggested by Ilengine.
I don't suppose this engine can be retrofitted for a fuel pump?
I am also wondering about that solenoid shutoff to prevent backfiring. It was awfully hot at the end of the mowing. I think there is a spring loaded needle that shuts off fuel flow to the engine unless the solenoid is pulling it open. Solenoids sometimes fail or weaken under high temperature. What if I just remove that spring so it stays open? I normally stop the engine by shutting off the fuel valve, so backfiring might not be an issue.
Chartman
C
Chartman
If it works every time from full to 3/4 then it is definately a fuel supply problem.
The pressure head is not enough to unseat the float needle.
Is this the same carb that the mower came with.
Fuel pumps run about 3 to 7 psi which while not much, is more than the pressure from a gravity head.
Gravity feeds use coarser filters than pressure fed ones.
Have a close look at the needle in the float and the seat.
Chances it is sticking a little.
Hi bertsmobile1. Thanks again for working with me on this problem.
I bought this lawn tractor used last year. There is nothing I see that suggests to me that the carburetor has been replaced, or even tampered with; but I cannot say for sure.
I think your suggestion of a sticky float needle is a good one. I haven't had the pleasure of disassembling the carb on this unit so far, but it seems like it might be in my near future.
I think it may be possible to get at those parts without removing the whole carb. It probably should not be done over the grass.
I will get the proper fuel filter as suggested by Ilengine.
I don't suppose this engine can be retrofitted for a fuel pump?
I am also wondering about that solenoid shutoff to prevent backfiring. It was awfully hot at the end of the mowing. I think there is a spring loaded needle that shuts off fuel flow to the engine unless the solenoid is pulling it open. Solenoids sometimes fail or weaken under high temperature. What if I just remove that spring so it stays open? I normally stop the engine by shutting off the fuel valve, so backfiring might not be an issue.
Chartman
#13
B
bertsmobile1
B
bertsmobile1
I thought you had already done the carb.
A little problem remembering exactly who has done what.
You will find the instructions for the carb here http://outdoorpowerinfo.com.
The shut off solenoid works by jambing a bung into the end of the main jet which stops any fuel getting into the engine instantly.
Down here they are not an EPA requirement so we just snip them off.
You can replace it with a short bolt for the purpose of elimination however in some places you ca get massive fines for tampering with it.
They do occasionally cause intermittent problems if the wires are broken at the terminal.
The fact that it only happens when the tank is 1/3 full or less still sounds like a pressure head problem or a restriction.
A little problem remembering exactly who has done what.
You will find the instructions for the carb here http://outdoorpowerinfo.com.
The shut off solenoid works by jambing a bung into the end of the main jet which stops any fuel getting into the engine instantly.
Down here they are not an EPA requirement so we just snip them off.
You can replace it with a short bolt for the purpose of elimination however in some places you ca get massive fines for tampering with it.
They do occasionally cause intermittent problems if the wires are broken at the terminal.
The fact that it only happens when the tank is 1/3 full or less still sounds like a pressure head problem or a restriction.
#14
C
Chartman
Hi Boudreaux. Thanks for taking the time to help me out!
It sounds to me like you think that the suction from the engine may be causing the rubber fuel lines to collapse because they have been degraded by the ethanol in the gas.
Hmmmm. They seemed to be pretty rigid as I was cleaning and blowing them out. I'll give them a squeeze next time they are hot and see what I think. I assume the remedy would be to replace those rubber lines. I do have some fresh stock.
I am confused by the fuel filter references. The filter I have, but did not install, is the 691035; a 40 Micron filter; rated for engines with a fuel pump. It appears that the filter recommended for my engine is the 394358S filter which is 75 Microns. This filter is white and smaller (I think). Wouldn't the 394358S be MORE restrictive of fuel flow because it is filtering smaller particles? More restrictive is not what I want.
I have no idea what filter came with my engine and is still on it. It is much larger than the 691035; mostly clear plastic but one end is a flat plate of metal. The element appears to be paper of some sort. I think I have seen this type of fuel filter in very old cars. The only marking I see says it was made in Taiwan. I should probably just replace that filter with the 691035 that I already have.
Chartman.
PS I don't think you'll be able to see through that open fuel valve.
C
Chartman
Ok in between my wife talking to me and trying to read all these post's...... I will comment .....
I agree with IL Engine about the filters...... I use the 691035 filters all the time on regular 8 HP Briggs and Techs the same size ......
The 691035 is a 40 Micron filter which is smaller than the 394358S filter which is 75 Microns. Not smaller in size, but smaller in the fact that it catches smaller particles of debris........
The 394358S is a small white filter and the other is a clear see thru filter.......And much bigger......
I did see see where you blew thru all the passages and then let the fuel flow from the tank into a container with no issue........
BUT even with NO fuel pump no matter what filter you have on there, the engine still works the same way with or without a fuel pump.... The engine sucks air into the carb via the intake stroke on a regular gravity feed tank..... With a fuel pump the engines are bigger and usually have bigger carbs and fuel usage / consumption.... So there is 2 ways to get more fuel to the carb and the piston / pistons.......
The only thing I can suggest is that your fuel lines are [flapping] on the inside...... Ethanol has took it's toll on them, and it don't take long... 1 month or 2 years ????
Even though you did empty the tank in a jar without the cap on or off doesn't mean anything.......... The fuel system is still under pressure with the carb doing it's normal work..... Even without the pump like I said earlier....
You got me curious though on not a see thru shut off valve ..... I have some in stock 698183 and bust a pack open and check that out and reply in a lil while ...........
Let us know Mon Ami ~!~!
Hi Boudreaux. Thanks for taking the time to help me out!
It sounds to me like you think that the suction from the engine may be causing the rubber fuel lines to collapse because they have been degraded by the ethanol in the gas.
Hmmmm. They seemed to be pretty rigid as I was cleaning and blowing them out. I'll give them a squeeze next time they are hot and see what I think. I assume the remedy would be to replace those rubber lines. I do have some fresh stock.
I am confused by the fuel filter references. The filter I have, but did not install, is the 691035; a 40 Micron filter; rated for engines with a fuel pump. It appears that the filter recommended for my engine is the 394358S filter which is 75 Microns. This filter is white and smaller (I think). Wouldn't the 394358S be MORE restrictive of fuel flow because it is filtering smaller particles? More restrictive is not what I want.
I have no idea what filter came with my engine and is still on it. It is much larger than the 691035; mostly clear plastic but one end is a flat plate of metal. The element appears to be paper of some sort. I think I have seen this type of fuel filter in very old cars. The only marking I see says it was made in Taiwan. I should probably just replace that filter with the 691035 that I already have.
Chartman.
PS I don't think you'll be able to see through that open fuel valve.
#15
C
Chartman
Hi JP. Thank you for weighing in!
I really cleaned that tank out well and I blew it out with compressed air. I pulled it right out of the tractor to work on it.
I agree that the symptoms suggest debris in the tank, but my troubleshooting suggests otherwise.
Chartman
C
Chartman
Hmmm,,,the "significant slope" statement would lead me to suspect debris in the tank sloshing around in the tank and occasionally blocking the fuel supply.
Regards
Jeff
Hi JP. Thank you for weighing in!
I really cleaned that tank out well and I blew it out with compressed air. I pulled it right out of the tractor to work on it.
I agree that the symptoms suggest debris in the tank, but my troubleshooting suggests otherwise.
Chartman
#16
C
Chartman
Hi Boobala, (...Boobala?)
Thanks for taking the time to weigh in on my problem.
I'm sorry you're having the same problem with your engine. I might try your "snake" mowing approach to help maintain fuel flow; but I would much rather see if I can fix the problem.
You say, "I'm sure it's the carburetor float..." but do you mean that this float is not working properly, or it is just what must be expected when mowing on a sloped lawn? Have you tried to "fix" the float?
This is enough of a problem for me that I would try to repair or replace the float to see if it fixes the problem. I will let you know how things turn out.
Chartman
C
Chartman
I have the same problem with my mower at times, only when mowing the slopes in my yard, I'm sure it's the carburetor float so I just get on the other side of the slope for a few seconds, now I mow up & down the slopes sideways up one and like a "snake" to the other side ( like mowing an "S" pattern ) as far as the filter goes it's normal for the amount of fuel in it to change (unless it's blocked of course) it seems your issue is on the slope, as you stated doing front yard, it was functioning OK I have the same engine 31c707 series but a 17.5 HP.
I completed the front yard with no problems and went straight on to the back without stopping.
About half way through, the same fuel starvation problem began. The engine sputtered every time the slope of the terrain tilted the fuel away from the engine.
Hi Boobala, (...Boobala?)
Thanks for taking the time to weigh in on my problem.
I'm sorry you're having the same problem with your engine. I might try your "snake" mowing approach to help maintain fuel flow; but I would much rather see if I can fix the problem.
You say, "I'm sure it's the carburetor float..." but do you mean that this float is not working properly, or it is just what must be expected when mowing on a sloped lawn? Have you tried to "fix" the float?
This is enough of a problem for me that I would try to repair or replace the float to see if it fixes the problem. I will let you know how things turn out.
Chartman
#17
Boudreaux In Eunice La.
Boudreaux In Eunice La.
The 394358S is 75 microns which it will not restrict fuel flow.... It's a smaller filter in size but has the bigger mesh inside of it.....
I opened a shut off valve and looked at it.... It is a bypass valve. That means the fuel goes around the center instead of straight thru.....
Hence the clogging sometimes.... Oh BTW you can't feel the flapping inside of the fuel lines... No actual way to check that in a normal garage without special tools...........
Plus Tard Mon Ami ~!~!
I opened a shut off valve and looked at it.... It is a bypass valve. That means the fuel goes around the center instead of straight thru.....
Hence the clogging sometimes.... Oh BTW you can't feel the flapping inside of the fuel lines... No actual way to check that in a normal garage without special tools...........
Plus Tard Mon Ami ~!~!
#18
Boudreaux In Eunice La.
Boudreaux In Eunice La.
Ok I got to haul ***** out a here and go do my Thursday nite radio show with Todd on KBON 101.1 FM
If anyone wants to listen go to KBON.com and on the homepage click on listen live or listen now.... It's free........
Plus Tard Mes Amies...........
If anyone wants to listen go to KBON.com and on the homepage click on listen live or listen now.... It's free........
Plus Tard Mes Amies...........
#19
C
Chartman
C
Chartman
This afternoon I decided to get back to the tractor and see what I could do.
With a needle nosed pliers I was able to remove the solenoid from the bottom of the carb cup. This also removed the cup. I decided I would leave the solenoid intact (in case I change my mind about removing it) and just replace it with a short machine screw. I had trouble figuring out the size, but it appears to be a metric 8 mm with 1.0 thread pitch. (Possibly 5/16 with 24 thread pitch?.) I had to cut down a longer cap screw. I had some trouble screwing it in more than a turn or two. Could this be a tapered thread? I ended up using a couple of washers to take up the space; I'm not proud of this job, but it seems to work. I saw no problems with the float and needle valve, but I did not take these off of the carburetor.
Based on the advice I received here, I decided to replace my unknown fuel filter with the 691035 filter, even though it was rated for engines with a fuel pump. I'm having a hard time imagining that the rubber hoses may be collapsing, but I did replace two short hoses; between the shutoff valve and filter, and between the filter and carb. I had the fuel line and the new hose might be a tighter fit; no vacuum leakage.
I decided to leave the fuel level of the tank where it was when I had the trouble last week and to mow just the back yard, which is most pitched.
The engine started immediately, as usual, and I was able to mow for about 10 - 15 minutes without problem, but then the same old symptoms recurred.
My lawn is level near the house, then sloped down hill for about 30 ft, then level again.
I tend to mow around the entire perimeter of the lawn and slowly spiral in toward the center.
The problems began when the engine was running hot, but also when I reached the point in the job where I was riding for long stretches in the pitched part of the lawn.
The sputtering began near the end of a stretch where the fuel tank was pitched away from the carburetor. When I reached the level part of the lawn, the engine typically recovered.
I quickly switched to a strategy similar to what Boobala recommended, using a serpentine mowing pattern, trying to minimize the time that the tractor was tilted in a problematic direction.
Things got worse as time went on and the level of gas in the tank got lower. I finished, ...but just barely. The fuel tank was perhaps a shade below half full.
So, this is looking more and more to me like a functional condition of this engine and tractor, rather than the failure of some particular part or system.
I think it will work fine if I keep the fuel tank VERY full, or mow only on level lawns.
There was no response to my inquiry about retrofitting a fuel pump to this engine, so I am guess that that is not a viable option.
I appreciate all of the responses and suggestions I have received to my inquiry.
It was very helpful and reassuring that I had not overlooked something simple.
Chartman
With a needle nosed pliers I was able to remove the solenoid from the bottom of the carb cup. This also removed the cup. I decided I would leave the solenoid intact (in case I change my mind about removing it) and just replace it with a short machine screw. I had trouble figuring out the size, but it appears to be a metric 8 mm with 1.0 thread pitch. (Possibly 5/16 with 24 thread pitch?.) I had to cut down a longer cap screw. I had some trouble screwing it in more than a turn or two. Could this be a tapered thread? I ended up using a couple of washers to take up the space; I'm not proud of this job, but it seems to work. I saw no problems with the float and needle valve, but I did not take these off of the carburetor.
Based on the advice I received here, I decided to replace my unknown fuel filter with the 691035 filter, even though it was rated for engines with a fuel pump. I'm having a hard time imagining that the rubber hoses may be collapsing, but I did replace two short hoses; between the shutoff valve and filter, and between the filter and carb. I had the fuel line and the new hose might be a tighter fit; no vacuum leakage.
I decided to leave the fuel level of the tank where it was when I had the trouble last week and to mow just the back yard, which is most pitched.
The engine started immediately, as usual, and I was able to mow for about 10 - 15 minutes without problem, but then the same old symptoms recurred.
My lawn is level near the house, then sloped down hill for about 30 ft, then level again.
I tend to mow around the entire perimeter of the lawn and slowly spiral in toward the center.
The problems began when the engine was running hot, but also when I reached the point in the job where I was riding for long stretches in the pitched part of the lawn.
The sputtering began near the end of a stretch where the fuel tank was pitched away from the carburetor. When I reached the level part of the lawn, the engine typically recovered.
I quickly switched to a strategy similar to what Boobala recommended, using a serpentine mowing pattern, trying to minimize the time that the tractor was tilted in a problematic direction.
Things got worse as time went on and the level of gas in the tank got lower. I finished, ...but just barely. The fuel tank was perhaps a shade below half full.
So, this is looking more and more to me like a functional condition of this engine and tractor, rather than the failure of some particular part or system.
I think it will work fine if I keep the fuel tank VERY full, or mow only on level lawns.
There was no response to my inquiry about retrofitting a fuel pump to this engine, so I am guess that that is not a viable option.
I appreciate all of the responses and suggestions I have received to my inquiry.
It was very helpful and reassuring that I had not overlooked something simple.
Chartman
#20
B
bertsmobile1
B
bertsmobile1
Fuel pumps are easy to fit but you will need a crankcase pressure take off point.
Easiest place is to fit a nipple to the rocker cover which saves having to drill a hole in the block.
Check the Briggs part list for your engine and see if there is a blanking off plug listed.
Some engines are drilled for fuel pumps even if the pump is not fitted while other will just have a boss cast in ready for drilling.
Drilling it will require splitting the cases to remove the swarf so drilling the rocker cover is a better choice.
From memory Vanguard cast alloy rocker covers will bolt directly onto your engine, but those more familiar with these engines than me will need to verify that.
If so get one of them and be careful where you make the hole so the nipple does not foul on the rockers.
Nipples come both threaded & plain so get a threaded one thus you will only need a thin lock nut inside to fix it in position.
Easiest place is to fit a nipple to the rocker cover which saves having to drill a hole in the block.
Check the Briggs part list for your engine and see if there is a blanking off plug listed.
Some engines are drilled for fuel pumps even if the pump is not fitted while other will just have a boss cast in ready for drilling.
Drilling it will require splitting the cases to remove the swarf so drilling the rocker cover is a better choice.
From memory Vanguard cast alloy rocker covers will bolt directly onto your engine, but those more familiar with these engines than me will need to verify that.
If so get one of them and be careful where you make the hole so the nipple does not foul on the rockers.
Nipples come both threaded & plain so get a threaded one thus you will only need a thin lock nut inside to fix it in position.
#21
Boudreaux In Eunice La.
Boudreaux In Eunice La.
Yes it can be a slope issue........... Yes the the rubber hoses can and will go south on you at any given time... I had a brand new top water hose on my 97 Silverado truck go south on me, also a earlier model truck 8 years before that.....
You said you took the CUP off of the carb..... That would be the bowl that holds the the gas in it.... Did the white assembly fall down ??
How many screws are holding the BOWL on your carb ?? Just the one bottom bolt or 2 extra small screws also ??
There is a noodle gasket that might be on your carb...... If that is not in the right EXACT place then it can be an issue.....
I myself have to take a NIKKI carb off to change that gasket..... It'a bugger alright ...........
Let us know Mon Ami ~!~!
You said you took the CUP off of the carb..... That would be the bowl that holds the the gas in it.... Did the white assembly fall down ??
How many screws are holding the BOWL on your carb ?? Just the one bottom bolt or 2 extra small screws also ??
There is a noodle gasket that might be on your carb...... If that is not in the right EXACT place then it can be an issue.....
I myself have to take a NIKKI carb off to change that gasket..... It'a bugger alright ...........
Let us know Mon Ami ~!~!
#22
C
Chartman
C
Chartman
Thank you B & B for your prompt and thoughtful responses.
After reading what you wrote I decided to go take a look at the engine and see if I could find out anything useful.
I found the state of affairs pretty discouraging.
First thing, I noticed the carb cup was dripping gas where I had made my "cob job" repair with the cap screw and washer spacers.
But why was there any gas there, since I shut down the fuel valve to shut off the engine?
Well, it turns out the expensive "fuel valve" shutoff I bought did not hold; and in fact I could barely turn it any more.
Although I found it amid a bunch of fuel valve shutoffs, I think it is made of plastic not rated for gasoline. Perhaps it is a potable water shutoff for RV's.
I now have the original shutoff back in place.
I am not sure how best to seal the carb cup (or perhaps it is called the "bowl"). I found a Briggs part 691657 Float Bowl Screw in the parts manual. Can this really cost >$8 and not even include the gasket seal?
I may have to reinstall that solenoid shutoff, although I'd rather not.
I also found other discouraging things like loose bolts, including one through a strut that apparently supports the front of the engine. It connects to the muffler, it seems.
There was also a missing specialty bolt that mounts the red plastic housing to the top of the engine.
I am afraid that someone with less than professional credentials and ethics (other than me) may have been monkeying with things.
RE Mon Frere, Boudreaux-
The carburetor "bowl" is anchored with only the solenoid screw (and now just a screw) through the hole in the bottom. For this reason, I don't think that the carb is a Nikki (but I may not know what I'm talking about).
I cannot tell if it is a Walbro or perhaps a Ruixing?
I find the parts manual very hard to understand. There are many pages of diagram that appear identical or at least very similar.
I'm guessing they are for variations within this engine category, but I can't tell what applies to me and what doesn't.
I don't know what a "noodle gasket" is, but from what I saw, the float moved up and down freely. I did not remove it from the carb.
I think I would remove the carb from the tractor before trying to mess with anything in it.
I have done this before, and I have replaced the float, needle valve and seat. As I recall, I had to thread a screw into the seat (thus ruining it) and jerry-rig a puller system to get it out.
I am getting to be a little "too chicken" to mess with things like that any more, I think.
RE Bertsmobile1
I looked through the parts manual, as stated. I could not find any part named "blanking off plug".
In a couple of places I found an item identified as "PLUG-(Crankcase Cover/Sump)" Briggs part # 794903. There is no clue in the diagram of where it might be found.
I saw nothing on the engine that looked like a plug to a port that might be used for a fuel pump.
If I understand your suggestion, I might be able to drill out a port in that shiny metal cover at the front of the engine? This would be the piece with the Briggs logo and "OHV"?
It is held on with four bolts and there is a gasket that would probably need to be replaced.
But before I attempt anything like that, I think I need to step back and consider all options.
I think I may be getting in over my head.
If I can manage by just keeping the fuel tank very full, I may just live with it that way (...for a while; ...until it really drives me crazy.)
I think my next test (next week when the lawn need mowing again) will be to fill the tank all the way and then head right to the steepest incline in the back yard and see what happens if I mow there for a while.
If there are no problems, I will probably just live with things as they are.
If the problem appears right away; ...well, I'm not sure what I will do.
Perhaps I need to buy a new house with a level lawn.
Chartman
After reading what you wrote I decided to go take a look at the engine and see if I could find out anything useful.
I found the state of affairs pretty discouraging.
First thing, I noticed the carb cup was dripping gas where I had made my "cob job" repair with the cap screw and washer spacers.
But why was there any gas there, since I shut down the fuel valve to shut off the engine?
Well, it turns out the expensive "fuel valve" shutoff I bought did not hold; and in fact I could barely turn it any more.
Although I found it amid a bunch of fuel valve shutoffs, I think it is made of plastic not rated for gasoline. Perhaps it is a potable water shutoff for RV's.
I now have the original shutoff back in place.
I am not sure how best to seal the carb cup (or perhaps it is called the "bowl"). I found a Briggs part 691657 Float Bowl Screw in the parts manual. Can this really cost >$8 and not even include the gasket seal?
I may have to reinstall that solenoid shutoff, although I'd rather not.
I also found other discouraging things like loose bolts, including one through a strut that apparently supports the front of the engine. It connects to the muffler, it seems.
There was also a missing specialty bolt that mounts the red plastic housing to the top of the engine.
I am afraid that someone with less than professional credentials and ethics (other than me) may have been monkeying with things.
RE Mon Frere, Boudreaux-
The carburetor "bowl" is anchored with only the solenoid screw (and now just a screw) through the hole in the bottom. For this reason, I don't think that the carb is a Nikki (but I may not know what I'm talking about).
I cannot tell if it is a Walbro or perhaps a Ruixing?
I find the parts manual very hard to understand. There are many pages of diagram that appear identical or at least very similar.
I'm guessing they are for variations within this engine category, but I can't tell what applies to me and what doesn't.
I don't know what a "noodle gasket" is, but from what I saw, the float moved up and down freely. I did not remove it from the carb.
I think I would remove the carb from the tractor before trying to mess with anything in it.
I have done this before, and I have replaced the float, needle valve and seat. As I recall, I had to thread a screw into the seat (thus ruining it) and jerry-rig a puller system to get it out.
I am getting to be a little "too chicken" to mess with things like that any more, I think.
RE Bertsmobile1
I looked through the parts manual, as stated. I could not find any part named "blanking off plug".
In a couple of places I found an item identified as "PLUG-(Crankcase Cover/Sump)" Briggs part # 794903. There is no clue in the diagram of where it might be found.
I saw nothing on the engine that looked like a plug to a port that might be used for a fuel pump.
If I understand your suggestion, I might be able to drill out a port in that shiny metal cover at the front of the engine? This would be the piece with the Briggs logo and "OHV"?
It is held on with four bolts and there is a gasket that would probably need to be replaced.
But before I attempt anything like that, I think I need to step back and consider all options.
I think I may be getting in over my head.
If I can manage by just keeping the fuel tank very full, I may just live with it that way (...for a while; ...until it really drives me crazy.)
I think my next test (next week when the lawn need mowing again) will be to fill the tank all the way and then head right to the steepest incline in the back yard and see what happens if I mow there for a while.
If there are no problems, I will probably just live with things as they are.
If the problem appears right away; ...well, I'm not sure what I will do.
Perhaps I need to buy a new house with a level lawn.
Chartman
#23
B
bertsmobile1
B
bertsmobile1
Yep thta is the place.
Kohler & some Hondas run the pump from the rocker cover.
Yes you should replace the gasket.
Put axel grease on the engine side and your favourite gasket gunk on the other side of the gasket then it will strip off clean and will last a long time if you don't do the bolts up too tight.
It is simple to do and should fix your problem.
It could even be you have a pump carb fitted and not a gravity carb fitted but don't have the information at hand to determine which one.
I have come across this sort of problem when swapping used engines which is usually fixed by swapping the carbs back.
Kohler & some Hondas run the pump from the rocker cover.
Yes you should replace the gasket.
Put axel grease on the engine side and your favourite gasket gunk on the other side of the gasket then it will strip off clean and will last a long time if you don't do the bolts up too tight.
It is simple to do and should fix your problem.
It could even be you have a pump carb fitted and not a gravity carb fitted but don't have the information at hand to determine which one.
I have come across this sort of problem when swapping used engines which is usually fixed by swapping the carbs back.
#24
Boudreaux In Eunice La.
Boudreaux In Eunice La.
Chartman........... I agree with Bert on the addition of a fuel pump....... You mentioned earlier that you had to JACK a seat out of the carb..... That is a Walbro carb.... I do those all the time.... The new seat has to be put back in the right way at the same level.....
If your float is dead level then you are in great shape.........
Watch this video. Mon Ami........... Is the second carb in the video yours ?????
If your float is dead level then you are in great shape.........
Watch this video. Mon Ami........... Is the second carb in the video yours ?????
#25
C
Chartman
Hi Bdrx,
That seat I "Jacked out" was on my old tractor, not this one. I mentioned it because that whole process made me pretty nervous. However, it was an old tractor and I didn't think it owed me much, if anything.
This tractor is much newer and in much better shape. I'd be really pissed at myself if I FUBAR'd it.
So that I understand you correctly, the float bottom should be "level". I am taking this to mean that when the float is in the "valve shut"/"bowl full of gas" position, the bottom surface of the float should be parallel to the circle on the carb that the bowl seats to. Is that correct?
I think you are telling me this to make sure that I get the valve seat "fully seated" if I end up replacing that part.
I remember I had to push it in firmly with the back end of the right sized drill bit when I replaced that seat on the other engine.
I don't see the link to the video you mentioned.
Will this forum allow you to send a plain text link?
CM
C
Chartman
Chartman........... I agree with Bert on the addition of a fuel pump....... You mentioned earlier that you had to JACK a seat out of the carb..... That is a Walbro carb.... I do those all the time.... The new seat has to be put back in the right way at the same level.....
If your float is dead level then you are in great shape.........
Watch this video. Mon Ami........... Is the second carb in the video yours ?????
Hi Bdrx,
That seat I "Jacked out" was on my old tractor, not this one. I mentioned it because that whole process made me pretty nervous. However, it was an old tractor and I didn't think it owed me much, if anything.
This tractor is much newer and in much better shape. I'd be really pissed at myself if I FUBAR'd it.
So that I understand you correctly, the float bottom should be "level". I am taking this to mean that when the float is in the "valve shut"/"bowl full of gas" position, the bottom surface of the float should be parallel to the circle on the carb that the bowl seats to. Is that correct?
I think you are telling me this to make sure that I get the valve seat "fully seated" if I end up replacing that part.
I remember I had to push it in firmly with the back end of the right sized drill bit when I replaced that seat on the other engine.
I don't see the link to the video you mentioned.
Will this forum allow you to send a plain text link?
CM
#26
Boudreaux In Eunice La.
Boudreaux In Eunice La.
#27
C
Chartman
LOL!
Yes, these guys are about my speed. Maybe even a little advanced.
I guess I have the Walbro carb. He mentions again that the Nikki had two screws holding the bowl in place, and I don't have that.
I did some poking around the inter-web to see what it might take to get a fuel pump running.
In as much I thought the simple nut to seal the bottom of the carb bowl was outrageously priced, I think they are practically giving away the fuel pump ($7 with free shipping?) I think I need a 808656 Briggs & Stratton; or equivalent.
I think the fuel lines are 1/4" so I need some of that and a nipple to attach to the "rocker arm cover(?)" after I drill a hole in it.
I might be willing to give this a try, since it looks like the worst that can happen is that I will need to replace that cover. How expensive could that be?
I guess my plan would be to not drill through the front large face, but to find a place on the edge, probably high or low on the port side of the tractor (nearer to the carburetor). I guess I won't know for sure until I take the cover off and see what it looks like inside.
I will also need a replacement gasket for this cover.
I have looked at some straight nipples that have a 1/4 barbed end for a rubber hose and a threaded (NPT) end. It seems like I would be better off with one that has a 1/4" NPT rather than the 1/8" NPT to allow better pressure pulses to pump the gas (as I understand the pump operation).
I will need a nut to secure the nipple to the cover and perhaps some kind of sealant to keep the system pressure tight.
I wonder if there are already holes on the engine somewhere to mount the pump? I am not worried about working something out if there aren't.
It seems "doable", but I'm not ready to jump in with both feet yet.
Maybe I'll just order the parts first and let them get comfortable in this environment for a while.
(I'll wait to hear if anyone thinks I am on the wrong track somewhere, before I do.)
Chartman
C
Chartman
LOL!
Yes, these guys are about my speed. Maybe even a little advanced.
I guess I have the Walbro carb. He mentions again that the Nikki had two screws holding the bowl in place, and I don't have that.
I did some poking around the inter-web to see what it might take to get a fuel pump running.
In as much I thought the simple nut to seal the bottom of the carb bowl was outrageously priced, I think they are practically giving away the fuel pump ($7 with free shipping?) I think I need a 808656 Briggs & Stratton; or equivalent.
I think the fuel lines are 1/4" so I need some of that and a nipple to attach to the "rocker arm cover(?)" after I drill a hole in it.
I might be willing to give this a try, since it looks like the worst that can happen is that I will need to replace that cover. How expensive could that be?
I guess my plan would be to not drill through the front large face, but to find a place on the edge, probably high or low on the port side of the tractor (nearer to the carburetor). I guess I won't know for sure until I take the cover off and see what it looks like inside.
I will also need a replacement gasket for this cover.
I have looked at some straight nipples that have a 1/4 barbed end for a rubber hose and a threaded (NPT) end. It seems like I would be better off with one that has a 1/4" NPT rather than the 1/8" NPT to allow better pressure pulses to pump the gas (as I understand the pump operation).
I will need a nut to secure the nipple to the cover and perhaps some kind of sealant to keep the system pressure tight.
I wonder if there are already holes on the engine somewhere to mount the pump? I am not worried about working something out if there aren't.
It seems "doable", but I'm not ready to jump in with both feet yet.
Maybe I'll just order the parts first and let them get comfortable in this environment for a while.
(I'll wait to hear if anyone thinks I am on the wrong track somewhere, before I do.)
Chartman
#28
B
bertsmobile1
B
bertsmobile1
One of the older L head engine ran the fuel pump off an arm moulded into the dip stick tube.
People who have been around longer than I might know the one I am thinking of.
All Briggs have the same size dip stick tube hole ( Vanguards are different ) so that might be an easy way to try before you start making holes in things.
The reason for using the rocker cover is it comes off so the swarf from making the hole does not end up in the engine.
Ferrit around for a flanged nipple so all that is inside is the flange and the nut ends up on the outside.
The big flange will also make a better seal and if you do go the rocker cover route, dot make a hole through the engine numbers stamped into the cover.
People who have been around longer than I might know the one I am thinking of.
All Briggs have the same size dip stick tube hole ( Vanguards are different ) so that might be an easy way to try before you start making holes in things.
The reason for using the rocker cover is it comes off so the swarf from making the hole does not end up in the engine.
Ferrit around for a flanged nipple so all that is inside is the flange and the nut ends up on the outside.
The big flange will also make a better seal and if you do go the rocker cover route, dot make a hole through the engine numbers stamped into the cover.
#29
C
Chartman
AH!
Now I get exactly what you mean about the flanged hose nipple. I will see if I can come up with one.
Now that you have mentioned it, I'm pretty sure that the "PT" in "NPT" means "pipe thread", so those connectors must have tapered threads, which is not really what I want.
I might be able to use a die to straighten out the taper then maybe use a nut on each side, but a flanged nipple definitely seems like the way to go, if I can find one.
Chartman
C
Chartman
One of the older L head engine ran the fuel pump off an arm moulded into the dip stick tube.
People who have been around longer than I might know the one I am thinking of.
All Briggs have the same size dip stick tube hole ( Vanguards are different ) so that might be an easy way to try before you start making holes in things.
The reason for using the rocker cover is it comes off so the swarf from making the hole does not end up in the engine.
Ferrit around for a flanged nipple so all that is inside is the flange and the nut ends up on the outside.
The big flange will also make a better seal and if you do go the rocker cover route, dot make a hole through the engine numbers stamped into the cover.
AH!
Now I get exactly what you mean about the flanged hose nipple. I will see if I can come up with one.
Now that you have mentioned it, I'm pretty sure that the "PT" in "NPT" means "pipe thread", so those connectors must have tapered threads, which is not really what I want.
I might be able to use a die to straighten out the taper then maybe use a nut on each side, but a flanged nipple definitely seems like the way to go, if I can find one.
Chartman
#30
B
bertsmobile1
We call these things different names down here so just look up whatever you call outlets from tanks over there.
The flanged ones are made for plastic tanks
Pipe threads come 2 ways
Taper & parallel
Taper is generally used for pipe joiners and parallel for all the rest.
If something is just labeled NP then it is NPP
B
bertsmobile1
AH!
Now I get exactly what you mean about the flanged hose nipple. I will see if I can come up with one.
Now that you have mentioned it, I'm pretty sure that the "PT" in "NPT" means "pipe thread", so those connectors must have tapered threads, which is not really what I want.
I might be able to use a die to straighten out the taper then maybe use a nut on each side, but a flanged nipple definitely seems like the way to go, if I can find one.
Chartman
We call these things different names down here so just look up whatever you call outlets from tanks over there.
The flanged ones are made for plastic tanks
Pipe threads come 2 ways
Taper & parallel
Taper is generally used for pipe joiners and parallel for all the rest.
If something is just labeled NP then it is NPP
#31
C
Chartman
C
Chartman
Hi, Anyone who cares...
Here is an update on my situation.
A week or so ago I needed to mow the front yard (less steep) lawn only.
I filled the gas tank very full. Then, just for kicks, I went right to the steepest part of the back lawn and mowed the full length (sideways along the slope) one lap in each direction.
This is about 100 ft or so each way. There was no problem with the engine.
I then continued on and had no problem mowing the front lawn.
It appears that if the tank is very full, the slope of the lawn is not a problem; at least with a "not too hot" engine.
Today I filled the tank VERY full (almost to the cap) and set about mowing the back yard.
I completed it with no problem.
The engine still sounded good, so I went straight to the front yard.
I completed that as well, but right at the very end I thought I heard the engine sound just a little less "energetic".
I let it idle (on fairly level ground) with the lower unit disengaged as I emptied the grass catcher for the last time.
I then shut the fuel valve so I could motor to its storage berth while the gas ran out of the carburetor.
This should have taken at least 30 to 60 sec, but the engine died in 5 seconds after I shut that valve.
It was clearly in a "starved for gas" state.
I opened the valve and watched the semi-transparent fuel filter.
Fuel did not "rush" in. I opened the fuel cap and still did not see a rush of fuel, but it did (mostly) fill up.
I had no problem starting it again and getting it back to storage.
The final state of the gas tank was at least 3/4 full.
The level of the fuel in the tank is clearly higher than the carburetor.
I am not sure what to make of all of this.
The hot engine may have something to do with it.
I don't think that I am in a bad way, since it appears that if I just fill the tank high before each use, I might be okay.
Perhaps that would be the prudent thing to do.
(...but it would be somewhat out of character, for me.)
If anyone has any thoughts on the subject, I'd love to hear them.
Chartman
Here is an update on my situation.
A week or so ago I needed to mow the front yard (less steep) lawn only.
I filled the gas tank very full. Then, just for kicks, I went right to the steepest part of the back lawn and mowed the full length (sideways along the slope) one lap in each direction.
This is about 100 ft or so each way. There was no problem with the engine.
I then continued on and had no problem mowing the front lawn.
It appears that if the tank is very full, the slope of the lawn is not a problem; at least with a "not too hot" engine.
Today I filled the tank VERY full (almost to the cap) and set about mowing the back yard.
I completed it with no problem.
The engine still sounded good, so I went straight to the front yard.
I completed that as well, but right at the very end I thought I heard the engine sound just a little less "energetic".
I let it idle (on fairly level ground) with the lower unit disengaged as I emptied the grass catcher for the last time.
I then shut the fuel valve so I could motor to its storage berth while the gas ran out of the carburetor.
This should have taken at least 30 to 60 sec, but the engine died in 5 seconds after I shut that valve.
It was clearly in a "starved for gas" state.
I opened the valve and watched the semi-transparent fuel filter.
Fuel did not "rush" in. I opened the fuel cap and still did not see a rush of fuel, but it did (mostly) fill up.
I had no problem starting it again and getting it back to storage.
The final state of the gas tank was at least 3/4 full.
The level of the fuel in the tank is clearly higher than the carburetor.
I am not sure what to make of all of this.
The hot engine may have something to do with it.
I don't think that I am in a bad way, since it appears that if I just fill the tank high before each use, I might be okay.
Perhaps that would be the prudent thing to do.
(...but it would be somewhat out of character, for me.)
If anyone has any thoughts on the subject, I'd love to hear them.
Chartman
#32
B
bertsmobile1
B
bertsmobile1
Nothing has changed from anything you have posted to date.
You do not have enough pressure head the get the fuel from the tank to the carb,
So either the carb float needle is sticking or mal adjusted and is not dropping like it should or something is obstructing the flow of fuel from the tank to the carb
You do not have enough pressure head the get the fuel from the tank to the carb,
So either the carb float needle is sticking or mal adjusted and is not dropping like it should or something is obstructing the flow of fuel from the tank to the carb
#33
M
Mark Sterling
M
Mark Sterling
I have a similar issue on a left side down slope.. I looked in tank seen some grass debris sucked it out. Took off all fuel lines, tank was full... all checked good replaced a couple of loose spring clamps...just in case. No help at all, I just read in this forum carb float bowl.. will have to take a look at that.. My scag is 20 years old now... changed oils and greased mostly all I have done... need to keep it running until I can get robot mowers for my 3 acres..Hmmm,,,the "significant slope" statement would lead me to suspect debris in the tank sloshing around in the tank and occasionally blocking the fuel supply.
Regards
Jeff
#34
M
Mark Sterling
M
Mark Sterling
I just cut off the needle point, as long as I choke it and put the gas lever in low I get no backfire..Hi bertsmobile1. Thanks again for working with me on this problem.
I bought this lawn tractor used last year. There is nothing I see that suggests to me that the carburetor has been replaced, or even tampered with; but I cannot say for sure.
I think your suggestion of a sticky float needle is a good one. I haven't had the pleasure of disassembling the carb on this unit so far, but it seems like it might be in my near future.
I think it may be possible to get at those parts without removing the whole carb. It probably should not be done over the grass.
I will get the proper fuel filter as suggested by Ilengine.
I don't suppose this engine can be retrofitted for a fuel pump?
I am also wondering about that solenoid shutoff to prevent backfiring. It was awfully hot at the end of the mowing. I think there is a spring loaded needle that shuts off fuel flow to the engine unless the solenoid is pulling it open. Solenoids sometimes fail or weaken under high temperature. What if I just remove that spring so it stays open? I normally stop the engine by shutting off the fuel valve, so backfiring might not be an issue.
Chartman
#35
S
slomo
S
slomo
Slope is probably too excessive for that mower. Splash lubed engines and slopes are not a good mix. So to me this is not a mower problem. Wrong tool for the job.
No pictures were provided of said slope. Is this a ski slope? The word slope was given telling me she's a steep one.
No pictures were provided of said slope. Is this a ski slope? The word slope was given telling me she's a steep one.