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B&S 440000 series V-Twin problem

#1

C

CWatters

I have a 440000 series B&S V-Twin in a Toro Wheelhorse that's giving me some trouble.

From cold it starts fine and cuts quite tall grass ok. However after about 40-50mins or running it bogs down/looses power. If I'm quick and turn off the cutter and drive the revs will come back up. Sometimes that doesn't happen and it will stop. It can be restarted again immediately. Sometimes if I give it a 3 min rest it will carry on for another 15-20 mins and bog again. Sometimes it bogs down again almost immediately and I have to give up and pack it away.

Next day/week it will be fine and do another 45mins work before going on strike again. The thing is it never packs up after say 10 mins so it's not just a case of it failing when warmed up. It takes longer than that.


I think I have ruled out:

Blocked fuel tank air vent.
Coil or Diode breakdown (replaced with new)
Spark plugs (replaced with new. Old plugs look clean, not oiled)
Fuel filter (replaced with new )
Fuel pump (replaced with new, including the pipe from valve cover to pump)
Valve guides moving in the head (They seem fine - all look same height)
Engine oil was replaced last season and still looks quite clean.


I'm beginning to think this is a fuel, carb or governor issue. Got any tips on how to narrow the problem down further?

I've noticed that the transparent fuel filter is never full of fuel, it always has a large air bubble in it. I've tried filling the filter with fuel using a syringe and it stayed full for one session. Today when I looked it was mostly air again. Any thoughts on how air is getting into the filter? I can't see any fuel leaks but perhaps I should just try replacing all the hoses anyway as they aren't expensive?


#2

Boobala

Boobala

CWatters said:
I have a 440000 series B&S V-Twin in a Toro Wheelhorse that's giving me some trouble.

From cold it starts fine and cuts quite tall grass ok. However after about 40-50mins or running it bogs down/looses power. If I'm quick and turn off the cutter and drive the revs will come back up. Sometimes that doesn't happen and it will stop. It can be restarted again immediately. Sometimes if I give it a 3 min rest it will carry on for another 15-20 mins and bog again. Sometimes it bogs down again almost immediately and I have to give up and pack it away.

Next day/week it will be fine and do another 45mins work before going on strike again. The thing is it never packs up after say 10 mins so it's not just a case of it failing when warmed up. It takes longer than that.


I think I have ruled out:

Blocked fuel tank air vent.
Coil or Diode breakdown (replaced with new)
Spark plugs (replaced with new. Old plugs look clean, not oiled)
Fuel filter (replaced with new )
Fuel pump (replaced with new, including the pipe from valve cover to pump)
Valve guides moving in the head (They seem fine - all look same height)
Engine oil was replaced last season and still looks quite clean.


I'm beginning to think this is a fuel, carb or governor issue. Got any tips on how to narrow the problem down further?

I've noticed that the transparent fuel filter is never full of fuel, it always has a large air bubble in it. I've tried filling the filter with fuel using a syringe and it stayed full for one session. Today when I looked it was mostly air again. Any thoughts on how air is getting into the filter? I can't see any fuel leaks but perhaps I should just try replacing all the hoses anyway as they aren't expensive?
Click to expand...

Air in the fuel filter is NORMAL, you say it runs fine for awhile, .. then your issue starts, seems you have done all the checks but, ... have you removed the engine shroud ( cowling ) and cleaned the engine cooling fins, it may be an overheating problem.. ??


#3

B

bertsmobile1

Yes there are really 2 possible causes,
1) overheating as already mentioned
2) loose or floating debris blocking the outlet of the fuel tank

When it starts to play up jump off remove the fuel cap, rip the fuel line off at the fuel pump and blow back up the line.
Hook it back up, if the problem goes away , for anothe 10 minutes of more then time to pull the tank


#4

L

Luffydog

Or if you have another known good clean tank that you can make an external tank out of and add clean fuel and try to what happens.


#5

Boobala

Boobala

WHY are you posting the SAME issue several times ........ it makes for confusion !!


#6

C

CWatters

Boobala said:
Air in the fuel filter is NORMAL..
Click to expand...

Thanks for that.

.. you say it runs fine for awhile, .. then your issue starts, seems you have done all the checks but, ... have you removed the engine shroud ( cowling ) and cleaned the engine cooling fins, it may be an overheating problem.. ??
Click to expand...

Yes I gave it a good check last year and again when I replaced the coils.


#7

C

CWatters

bertsmobile1 said:
Yes there are really 2 possible causes,
1) overheating as already mentioned
2) loose or floating debris blocking the outlet of the fuel tank

When it starts to play up jump off remove the fuel cap, rip the fuel line off at the fuel pump and blow back up the line.
Hook it back up, if the problem goes away , for anothe 10 minutes of more then time to pull the tank
Click to expand...

I'll try that but have already tried disconnecting the fuel line at the filter and fuel flows out of the pipe with no problems.


#8

C

CWatters

Luffydog said:
Or if you have another known good clean tank that you can make an external tank out of and add clean fuel and try to what happens.
Click to expand...

I've got some fuel hose on order and will try rigging up a temporary tank behind the seat.


#9

C

CWatters

Boobala said:
WHY are you posting the SAME issue several times ........ it makes for confusion !!
Click to expand...

Sorry about that.


#10

B

bertsmobile1

CWatters said:
I'll try that but have already tried disconnecting the fuel line at the filter and fuel flows out of the pipe with no problems.
Click to expand...

Grass in a fuel tank does not decompose.
It goes translucent and floats in the fuel.
AS fuel is drawn out of the tank this debris is pulled into the outlet ( thats good English ain't it ) blocking or partially blocking off the outlet thus starving the mower of fuel.
When the mower is off and there is no current to draw the flotsum into the outlet, it floats away and distributes itself around the tank till you run the mower again.


#11

Boudreaux In Eunice La.

Boudreaux In Eunice La.

I got a story to tell about a mosquito leg in a carb ~!~!


#12

B

bertsmobile1

Boudreaux In Eunice La. said:
I got a story to tell about a mosquito leg in a carb ~!~!
Click to expand...

Well I had a wasp slip into a fuel line on the bike when the tank was off overnight.
The now dead body sat there causing no problems for 2 full days of riding ( 1200 km ) .
Then we stopped to check a billboard map, and I left the engine running.
During this time the wasp broke up and partially clogged he fuel filter in the carb banjo so it was another 300 km restricted to 1/2 throttle.


#13

Boudreaux In Eunice La.

Boudreaux In Eunice La.

CWatters said:
I have a 440000 series B&S V-Twin in a Toro Wheelhorse that's giving me some trouble.

From cold it starts fine and cuts quite tall grass ok. However after about 40-50mins or running it bogs down/looses power. If I'm quick and turn off the cutter and drive the revs will come back up. Sometimes that doesn't happen and it will stop. It can be restarted again immediately. Sometimes if I give it a 3 min rest it will carry on for another 15-20 mins and bog again. Sometimes it bogs down again almost immediately and I have to give up and pack it away.

Next day/week it will be fine and do another 45 mins work before going on strike again. The thing is it never packs up after say 10 mins so it's not just a case of it failing when warmed up. It takes longer than that.


I think I have ruled out:

Blocked fuel tank air vent.
Coil or Diode breakdown (replaced with new)
Spark plugs (replaced with new. Old plugs look clean, not oiled)
Fuel filter (replaced with new )
Fuel pump (replaced with new, including the pipe from valve cover to pump)
Valve guides moving in the head (They seem fine - all look same height)
Engine oil was replaced last season and still looks quite clean.


I'm beginning to think this is a fuel, carb or governor issue. Got any tips on how to narrow the problem down further?

I've noticed that the transparent fuel filter is never full of fuel, it always has a large air bubble in it. I've tried filling the filter with fuel using a syringe and it stayed full for one session. Today when I looked it was mostly air again. Any thoughts on how air is getting into the filter? I can't see any fuel leaks but perhaps I should just try replacing all the hoses anyway as they aren't expensive?
Click to expand...

Ok are you sure you are running on both cylinders all the time ???? Those V twins will run on one and then die out when you engage the blades........ Ok I shouldn't have said that first.....

The next thing is that FUEL lines can go bad inside of them..... Even though they pass gas LOL Excuse the PUN...... They will not pass gas properly thru the fuel lines under pressure...... They go bad on the inner lining and restrict fuel....... You can blow them all you want and let them drip on a gravity situation, BUT under pressure it's a no go.....

Just some more free advice for you Mon Ami ~!~!

Let us Know ......................


#14

C

CWatters

Boudreaux In Eunice La. said:
Ok are you sure you are running on both cylinders all the time ???? Those V twins will run on one and then die out when you engage the blades........
Click to expand...

I'll see if I can test that next time the problem occurs.

My gut feeling is that it's not a spark issue because in the past I've accidentally run it with one plug lead disconnected and it seems to have more power and run more smoothly on one cylinder than it does when the problem occurs.


#15

Boobala

Boobala

I'm sure this has nothing to do with it, but since you've tried most everything that is an apparent cause, have you checked the fuel filter for the right MICRON size ..?? some filters are required for certain engines, read the description of the filters... and also here's some info on that "trashy" fuel line stuff.....

FUEL FILTERS.JPG..NOTICE OF FAILURE.PNG..BAD FUEL LINE.jpg


#16

C

CWatters

Boobala said:
I'm sure this has nothing to do with it, but since you've tried most everything that is an apparent cause, have you checked the fuel filter for the right MICRON size ..?? some filters are required for certain engines, read the description of the filters... and also here's some info on that "trashy" fuel line stuff.....

View attachment 37612..View attachment 37613..View attachment 37614
Click to expand...


Thanks for that. Not checked the filter micron size as I don't think I have data on the one on the machine.

Just went out to see if there was anything written on the hose but can't see any markings on it. Still waiting for the new stuff to arrive.


#17

C

CWatters

Just noticed that the fuel filter appears to have filled itself up - all the air seems to have gone. Very surprised as it's hard to see how _all_ of the air could get out. The thing is nearly horizontal so I would have expected some air to be trapped at the top.

I need to have another look this weekend as it's a bit dark to see at the moment. Hopefully the new pipe will also have arrived by then.

Thanks for all the ideas so far.


#18

C

CWatters

Possibly solved see

http://www.lawnmowerforum.com/showt...ble-coil-fault?p=295745&viewfull=1#post295745


#19

Boudreaux In Eunice La.

Boudreaux In Eunice La.

I copied and pasted for you Mon Ami .............

Possibly solved...

Ok so yesterday I drained the tank and replaced all the fuel lines from tank to carb. Some of the lines looked like they might have tiny cracks/splits near where they connected to things like the tank or fuel switch. I don't think any went right through and no fuel leaks detected.

I let the tank dry out with the filler cap off and had a look inside before vacuuming out the inside. There was some debris in there but I couldn't say anything was a definite candidate to block the outlet.

However I was surprised how small the fuel outlet was. I didn't measure it but it was slightly under 3mm (<1/8") so I can see how a blockage might occur. There is also no "upstand" so if you do run out of gas anything in there could go down the fuel pipe.

Anyway I filtered the gas and put that back in. Today I spent nearly two hours cutting grass and it didn't cut out on me! It did hiccup but that was when I was going over some rather bumpy ground.

It's a bit early to say it's solved/fixed because the grass was quite short but I will post back here to confirm.


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