Last effort before service center Intek 20hp V Twin

[StatesboroMike]

I have a Poulan Pro PP20VA46 lawn tractor that is about a year old. It has a B&S 20hp Intek V-Twin engine. Code is 40N877-0004G1-170627YG. It ran perfectly until a few months ago when someone broke into my shed and stole all my fuel, including draining the tanks of all of my gas-powered equipment (I have a suspect but no proof ). It began surging badly after that. I took apart the carb and gave it a good cleaning. I also did the same for the fuel tank and lines. After that it ran smoothly until a few weeks ago when it began surging again. Once more I took apart the carb and cleaned it but the surging continued. After taking it apart and cleaning it a second time the governor gear exploded (my fault, I misadjusted it). I have since replaced the governor (and I made sure I found all the pieces of the exploded governor) and adjusted it according to the procedure outlined in a service manual another member here was kind enough to send to me. In fact, I have given it what amounts to a full service. Here is what I have done:
replaced fuel, air, and oil filters
cleaned mower deck and frame of debris
sharpened blades
leveled deck and adjusted gauge wheels
adjusted governor and throttle linkage per service manual
changed oil
cleaned fuel system (I use 89 Octane btw)
replaced spark plugs
installed new o rings in carb float bowl
replaced carb manifold gaskets
Cleaned the fuel pump
greased all lubrication points with lithium based marine grease (recommended by another member here)
aired all tires to proper psi
replaced choke return spring


After all this, I am STILL having issues! It starts fine and continues to run but only at full throttle and that roughly. Even then it seems to be operating at a much lower rpm than Fast mode implies. If I throttle down it starts to surge badly. It also surges and loses power when I engage the blades. Even without a load it runs sluggishly just driving it around.

So what could be the issue? I've heard of other people with similar engines having to replace the entire carb. Could this be it? Or could it have something to do with the valves? Or could it be something else entirely? This is my Hail Mary effort before taking it to a professional or taking my sledgehammer to it and buying a new engine. Any input will be greatly appreciated. PS: I did use a liquid gasket maker rather than purchasing a premade gasket for the engine. I'm sure I did a thorough job in sealing the engine case however. Should I crack it open again and replace it with a premade gasket?

 

[shiftsuper175607]

I have a Poulan Pro PP20VA46 lawn tractor that is about a year old. It has a B&S 20hp Intek V-Twin engine. Code is 40N877-0004G1-170627YG. It has run perfectly until a few months ago when someone broke into my shed and stole all my fuel, including draining the tanks of all of my gas-powered equipment (I have a suspect but no proof ). It began surging badly after that. I took apart the carb and gave it a good cleaning. I also did the same for the fuel tank and lines. After that it ran smoothly until a few weeks ago when it began surging again. Once more I took apart the carb and cleaned it but the surging continued. After taking it apart and cleaning it a second time the governor gear exploded (my fault, I misadjusted it). I have since replaced the governor (and I made sure I found all the pieces of the exploded governor) and adjusted it according to the procedure outlined in a service manual another member here was kind enough to send to me. In fact, I have given it what amounts to a full service. Here is what I have done:
replaced fuel, air, and oil filters
cleaned mower deck and frame of debris
sharpened blades
leveled deck and adjusted gauge wheels
adjusted governor and throttle linkage per service manual
changed oil
cleaned fuel system (I use 89 Octane btw)
replaced spark plugs
installed new o rings in carb float bowl
replaced carb manifold gaskets
Cleaned the fuel pump
greased all lubrication points with lithium based marine grease (recommended by another member here)
aired all tired to proper psi
replaced choke return spring


After all this, I am STILL having issues! It starts fine and continues to run but only at full throttle and that roughly. Even then it seems to be operating at a much lower rpm than Fast mode implies. If I throttle down it starts to surge badly. It also surges and loses power when I engage the blades. Even without a load it runs sluggishly just driving it around.

So what could be the issue? I've heard of other people with similar engines having to replace the entire carb. Could this be it? Or could it have something to do with the valves? Or could it be something else entirely? This is my Hail Mary effort before taking it to a professional or taking my sledgehammer to it and buying a new engine. Any input will be greatly appreciated. PS: I did use a liquid gasket maker rather than purchasing a premade gasket for the engine. I'm sure I did a thorough job in sealing the engine case however. Should I crack it open again and replace it with a premade gasket?

It does not cost anything to check the valve clearances. It's worth a shot.

sorry for your misfortune with the vandals...a pox upon them.

How much does a new carb cost?

yet yours is only a year old....hmmm

Check that all your throttle and choke rods etc are in the correct place...maybe something is in the wrong spot or binding

 

[Boudreaux In Eunice La.]

Mike I never use a tube of gasket maker if there is a gasket available.......... Where did you use it at.... ???

Your surge issue has to do with fuel. You carb is still dirty inside in some other hard to reach areas...... You more than likely have the Nikki 2 barrel carb on yours and those kits are pricey,,,,,

I would invest in a ultrasonic cleaner and watch a few videos on you tube on your carb... Just cleaning a bowl doesn't cut the mustard on those finicky carbs.......

Harbor freight has those cleaners for cheap......

Let us know Mon Ami ~!~!

 

[StatesboroMike]

Mike I never use a tube of gasket maker if there is a gasket available.......... Where did you use it at.... ???

Your surge issue has to do with fuel. You carb is still dirty inside in some other hard to reach areas...... You more than likely have the Nikki 2 barrel carb on yours and those kits are pricey,,,,,

I would invest in a ultrasonic cleaner and watch a few videos on you tube on your carb... Just cleaning a bowl doesn't cut the mustard on those finicky carbs.......

Harbor freight has those cleaners for cheap......

Let us know Mon Ami ~!~!

I used the gasket maker to seal the main crankcase halves together. Its use was recommended to me by a neighbor who is a diesel mechanic and I watched several videos before using it. I don't believe it is causing the issue. My engine uses a single barrel carb with dual manifold. Pics are attached below. I soaked the carb in Seafoam cleaner overnight before installing it and used at least two cans of carb cleaner on it, spraying in every hole I could find as well as the entire frame. It must be cleaner now than when it came off the assembly line. Still, could it be the problem? Or could it be something to do with the valves? I'm losing my mind with the effin thing.

 

[Boudreaux In Eunice La.]

Mike post the model # of the engine for me It's gonna be on the driver side valve cover that way I can see what carb you have.....

Then I can tell you more..... Surging comes from the idle circuit most of the time...... There will be a welch plug on the side of the carb, and that has to come out and then soaked then cleaned well....

I have toooo many like that one....... I can then tell you what kit to get..... Those single barral are a lot cheaper than the 2 barrel type.........

Let us know Mon Ami ~!~!

 

[Boudreaux In Eunice La.]

Never mind about the model number........ I see it in the first post you did .............. Oops

 

[Boudreaux In Eunice La.]

Ok here's the parts you will need.........

699810 Welch plug

698781 Noodle bowl gasket....

Gonna have tooooooo take welch plug out and the rest of the carb apart.... Give it a good soaking for a few hours in a bath of carb cleaner or a ultrasonic cleaner.....

There will be some holes ( TINY ) under the welch plug that is your idle circuit and causing your surging issue....... Those tiny holes need to be cleaned well... Varnish and ethanol junk from e gas is built up in there.......

Let us know Mon Ami ~!~!

 

[cpurvis]

I have a Poulan Pro PP20VA46 lawn tractor that is about a year old. It has a B&S 20hp Intek V-Twin engine. Code is 40N877-0004G1-170627YG. It ran perfectly until a few months ago when someone broke into my shed and stole all my fuel, including draining the tanks of all of my gas-powered equipment (I have a suspect but no proof ). It began surging badly after that. I took apart the carb and gave it a good cleaning. I also did the same for the fuel tank and lines. After that it ran smoothly until a few weeks ago when it began surging again. Once more I took apart the carb and cleaned it but the surging continued. After taking it apart and cleaning it a second time the governor gear exploded (my fault, I misadjusted it). I have since replaced the governor (and I made sure I found all the pieces of the exploded governor) and adjusted it according to the procedure outlined in a service manual another member here was kind enough to send to me. In fact, I have given it what amounts to a full service. Here is what I have done:
replaced fuel, air, and oil filters
cleaned mower deck and frame of debris
sharpened blades
leveled deck and adjusted gauge wheels
adjusted governor and throttle linkage per service manual
changed oil
cleaned fuel system (I use 89 Octane btw)
replaced spark plugs
installed new o rings in carb float bowl
replaced carb manifold gaskets
Cleaned the fuel pump
greased all lubrication points with lithium based marine grease (recommended by another member here)
aired all tires to proper psi
replaced choke return spring

Most of this has nothing to do with surging. Getting the carburetor CLEAN has everything to do with it. Spraying with a pressurized can rarely gets the internal passages clean. If you're not going to clean it properly, get a new carburetor.

PS: I did use a liquid gasket maker rather than purchasing a premade gasket for the engine. I'm sure I did a thorough job in sealing the engine case however. Should I crack it open again and replace it with a premade gasket?

I'm not familiar with your engine, but some engines control crankshaft end play with this gasket.

 

[StatesboroMike]

Most of this has nothing to do with surging. Getting the carburetor CLEAN has everything to do with it. Spraying with a pressurized can rarely gets the internal passages clean. If you're not going to clean it properly, get a new carburetor.


I'm not familiar with your engine, but some engines control crankshaft end play with this gasket.

This is my first time trying to repair anything mechanical, teaching myself and learning as I go in order to be more self-sufficient. Until yesterday I didn't even know what a Welch plug was and everything I listed was to show how thorough I am trying to be for the engine and the overall unit. Later this morning I will be taking the carb apart yet again to clean it as suggested. As far as the gasket it concerned, I haven't found anything to suggest it has anything to do with the crankshaft end play. In will research further. I am still wondering if the valves are part of the problem. Thanks for the input.

 

[StatesboroMike]

This is my first time trying to repair anything mechanical, teaching myself and learning as I go in order to be more self-sufficient. Until yesterday I didn't even know what a Welch plug was and everything I listed was to show how thorough I am trying to be for the engine and the overall unit. Later this morning I will be taking the carb apart yet again to clean it as suggested. As far as the gasket it concerned, I haven't found anything to suggest it has anything to do with the crankshaft end play. In will research further. I am still wondering if the valves are part of the problem. Thanks for the input.

Update: I removed the carb again today, located and removed the welch plug. I tried to be careful getting it out but...well, I have two on order now. Do I need to seal the new plug? Anyway, I used about half a can of carb cleaner on every part of the carb and now have the main unit soaking in a cleaner. I admit I'm new to repairing a motor but considering I have repeatedly sprayed and soaked every inch of the carb before this I honestly dont see how it could be the cause of my current issues. It should be clean to the point of....something....lol

Tomorrow I am going to check the valve clearances and compression and i'm considering removing the flywheel to check the key for damage. These are the only other things my research as suggested as possible sources of the low power and surging. Is there anything else I should check?