the saga continues... PT-425 engine problem at 10 hours?

[dcdtn]

After doing about 2 hours of loader work today the PT started sputtering. Thinking I was about out of gas I rushed back to the garage to fill it up. It still had almost half a tank, but filled up anyway. I also checked to make sure the fuel line didn't get kinked from where I replaced the gas tank.

After filling up, I didn't get far before engine died. I had to use full choke to get it started again. It seems to run ok at half throttle, but sputters at full throttle. I let it run at idle for 15 minutes or so and then shut it down... then it backfired.

Other info that may or may not be pertinent... I've noticed some oil on the metal disc of the air filter. Also since new, I've noticed when shutting down it still tries firing a few times like it wants to keep running.

I don't think there is a fuel quality issue since I have been using the same batch of 0% ethanol fuel without issue.

The fuel filter bulb seems to be only about half full of fuel... Don't know whether that is normal or not?

Any ideas?

 

[ernemats]

I would start by checking the fuel line for having pieces of silicone sealant or pieces of plastic from gas tank fitting blocking gas flow. I know I had a problem with that when new and I think others have had similar problems

 

[Frank Sorbello]

Check your oil level. Make sure it isn't rising. Do you have a gas shut off valve under the tank?

 

[dcdtn]

I would start by checking the fuel line for having pieces of silicone sealant or pieces of plastic from gas tank fitting blocking gas flow. I know I had a problem with that when new and I think others have had similar problems

Good idea. I'm really hoping this is the case. It would explain not running well full throttle.

 

[dcdtn]

Check your oil level. Make sure it isn't rising. Do you have a gas shut off valve under the tank?

Oil level seems consistent since I bought it. No gas shut off valve from factory that I can see.

 

[Frank Sorbello]

Do yourself a favor. Buy a two dollar inline shut off valve and install it between the tank and fuel pump. When the tractor is not in use shut off the valve. It has happened to me, and have seen it a lot on here where the gas finds it way into the crankcase.

 

[KentT]

Good idea. I'm really hoping this is the case. It would explain not running well full throttle.

Certainly sounds like fuel starvation. Running lean also means running hot, which could be causing it trying to run on when you shut it off. If you have a compressor, try removing the fuel hose in front of the filter and blowing compressed air back up into the tank. I had to do that more than once over my 425's life...

 

[dcdtn]

Do yourself a favor. Buy a two dollar inline shut off valve and install it between the tank and fuel pump. When the tractor is not in use shut off the valve. It has happened to me, and have seen it a lot on here where the gas finds it way into the crankcase.

Will do. Thanks for heads up!

 

[dcdtn]

Certainly sounds like fuel starvation. Running lean also means running hot, which could be causing it trying to run on when you shut it off. If you have a compressor, try removing the fuel hose in front of the filter and blowing compressed air back up into the tank. I had to do that more than once over my 425's life...

I'll give it a try. Hopefully that will do the trick. It will be a few days before I can get to it, though.

 

[Marks481]

I would start by checking the fuel line for having pieces of silicone sealant or pieces of plastic from gas tank fitting blocking gas flow. I know I had a problem with that when new and I think others have had similar problems

Specifically, check inside the elbow at the bottom of the fuel tank. MANY of those here have ended up with chunks of sealant in there left over from tank manufacture.

The backfiring and dieseling (running after shutdown) is normal. The exhaust manifold is insanely hot because the exhaust header and muffler are poorly designed. If you do a little searching you will find that quite a few of us have got rid of the stock header and muffler and replaced it with the Robin header and muffler, which seems to help.

These little tractors have problems with vapor lock, although it seems that it is probably cool enough out (YMMV) that this shouldn't be as much of an issue. The fuel pump is mounted on the same side of the tractor as the muffler, which seems to contribute to this...easy enough to relocate the pump.... nothing magical about that location. The pump is driven by pulsating pressure through a 1/4" line plumbed off the crankcase. You can put the pump anywhere you want.