Yanmar loses power, slows down & kills

[tallyho8]

That is great Tally that you can and that your tractor is usable, but boy is that nagging that it is NOT right like it should be. Where is that air coming from and why does it enter the system? I have spent a fair amount of time thinking about those question, and have not come up with anything.

Mike

As previously mentioned, I installed a clear fuel line and can see bubbles coming into the line from the injector pump when I lower the throttle.

I do not know why, wish I did, that is the big question.

 

[MJPetersen]

Yes I remember that you identified the source as the pump, but where in the pump is the air getting in. That is what I meant. Yes it is a bit frustrating.

Mike

 

[greatrandini]

Did you ever replace that old hard plastic fuel bowl?

 

[tallyho8]

Did you ever replace that old hard plastic fuel bowl?

No, I didn't. It sure doesn't seem like it has any leaks.

 

[dqdave1]

compression test

 

[tallyho8]

compression test

I've never done a compression test on it, but it is starting instantly even in cold weather, and running perfectly with it rigged the way I have it. I would be willing to bet that the compression is perfect.

 

[scottr5150]

Read through this whole post. Oddly enough have what sounds to be a very similar problem with a Ford/New Holland tractor. It's a 28 HP 3 cyl with what sounds like a similar fuel system consisting of a sediment bowl, filter, etc... My issues typically happened while mowing and under a lot of a load. Now their more frequent to the point the tractor is not usable other than for loader work. The odd thing is when I put a new fuel filter in last summer, thinking that was the problem, it seemed to get worse. Think I'll start my quest there. I live in Northern Iowa and have not had an issue in the winter or when cold. Apprieciate this post and everything you have endured as it should help me. Do you still have the problem?

Thanks!!

 

[tallyho8]

Read through this whole post. Oddly enough have what sounds to be a very similar problem with a Ford/New Holland tractor. It's a 28 HP 3 cyl with what sounds like a similar fuel system consisting of a sediment bowl, filter, etc... My issues typically happened while mowing and under a lot of a load. Now their more frequent to the point the tractor is not usable other than for loader work. The odd thing is when I put a new fuel filter in last summer, thinking that was the problem, it seemed to get worse. Think I'll start my quest there. I live in Northern Iowa and have not had an issue in the winter or when cold. Apprieciate this post and everything you have endured as it should help me. Do you still have the problem? Thanks!!

No, I have had no problem since I made my air line.

 

[guyd]

Hi - newbie here. YM1510 in the UK here...

Sorry to drag this back up - but I have had an almost identical problem. It would start easily and run fine, until it was warm. Then, only when using significant throttle, ie more than 1/3rd, it would bog down, slow, seemingly running on 1 or 2 cylinders, and I tried to keep it running by flooring the throttle, and most of the time it would catch back on and keep running. If it died, it would start again instantly on the key. If I left it on tickover or only very small throttle openings, it would drive around all day.

I replaced the fuel lines, but being lazy, didnt bother with the 'jubilee clips' or worm drive clamps. The problem was the same. The installation of hose clamps has fixed the problem - it was air getting in.

 

[guyd]

actually - update to this situation. Continued use at high throttle openings has resulted in the same problem.

I wondered if heat was an issue, so poured cool water on the injector area of the engine. this appeared to fix the problem for a bit. reapeat three times, same result whilst flail mowing some 3 feet high grass for the guy next door. ran much much better shortly after the cold water treatment.