Kubota L3710 runs for 20 minutes then won't run at speed or at all.

[Garman906]

Hello,

I'm hoping to get some insight to a fuel related problem that I have been fighting for about a week now. I was going to bush-hog my property and my tractor started right up after a long winter nap. I made several rounds around one field, approximately 20 minutes worth and the engine lost power and slowed way down. I limped it back to my garage and checked the fuel filter. It was dirty so I changed it and thought that everything would be ok. Started working again and approximately 20 minutes later, same thing. I have now replaced the fuel filter, lifter pump, all fuel lines and still have the same problem. I even removed the fuel tank and removed a stick and an old spout from a fuel can from it. I removed the fuel filter assembly and disassembled and cleaned it. I'm getting kind of desperate and thinking it may be something inside the injector pump. I don't really know exactly how the fuel flows through the injector pum or how to remove and replace it. It seems like if I remove a line or filter or just let it sit for a while it will start and run for another short spurt.

Any help would be greatly appreciated.

 

[ptsg]

Try this test. Run it for the 20 min or so it runs decent, then when it starts acting up, try taking the fuel cap off and keep running to see if it changes anything.

It's not uncommon for the vent on the cap to get plugged over time with dirt, dust, etc and causing similar issues.

 

[Garman906]

Thanks, I'll try that. Will update shortly.

 

[Garman906]

Try this test. Run it for the 20 min or so it runs decent, then when it starts acting up, try taking the fuel cap off and keep running to see if it changes anything.

It's not uncommon for the vent on the cap to get plugged over time with dirt, dust, etc and causing similar issues.

I tried that and got the same results.

 

[seville009]

How about your air filter? I always check that each spring before starting it due to critters nesting in it over the winter (and shredding the filter). Maybe it is clogged up.

 

[Garman906]

I've completely removed the air filters just for testing purposes and there was no change. I had just replaced both filters last year and they really aren't dirty.

 

[seville009]

When you say that the engine slows way down, is it still running smooth (like it would if you intentionally reduced the throttle), or is it sputtering/missing/rough?

 

[rbargeron]

Mouse or squirrel nest in the muffler? Something expanding with heat and plugging it up? Pet food? Acorns?

 

[Garman906]

When you say that the engine slows way down, is it still running smooth (like it would if you intentionally reduced the throttle), or is it sputtering/missing/rough?

It slows down smooth like it is running out of fuel., and has no power

 

[Garman906]

Mouse or squirrel nest in the muffler? Something expanding with heat and plugging it up? Pet food? Acorns?

Now that is something that I had not thought about. Not even sure how to check it, but I'll give it a whirl tomorrow. It does blow black smoke when I try to start it after it dies. Then after it sits a while it cranks right back up and runs great for another 15 - 20 minutes.