Yanmar loses power, slows down & kills

[jtshine]

I've solved this problem. It just happened to me. The one thing nobody checked was the O Ring on the fuel shutoff valve above the filter. Took mine off, soaked it in brake fluid for a hour, the tractor runs beautiful, does not cut out at all. Hope this helps anybody else out there with the same problem.

 

[SPYDERLK]

Thread alternate title: Tractor has serious Snit culminating in murder.

 

[irwin]

Thread alternate title: Tractor has serious Snit culminating in murder.

After losing a re-election bid the tractor took it easy for a while before resorting to murder.

 

[irwin]

I've solved this problem. It just happened to me. The one thing nobody checked was the O Ring on the fuel shutoff valve above the filter. Took mine off, soaked it in brake fluid for a hour, the tractor runs beautiful, does not cut out at all. Hope this helps anybody else out there with the same problem.

Welcome to TBN jtshine, good to have you here. Thanks for posting your fix.

 

[tallyho8]

I wish that my original problem could have been solved so easily! As mentioned in earlier threads, I even used a fuel can and ran the line straight to the injector pump, eliminating the fuel filters, tanks, lines etc. and the tractor did the same thing.

But since I rigged up my air-line on it, I have had no problems whatsoever, and still love using my Yanmar for all the small and odd jobs around here.

 

[Ron D.]

This site really rocks. I have a F13D that I was using yesterday and it all of a sudden started losing power and died. I looked around the fuel components and saw the fuel bowl was full, so I felt it wasn't a supply issue to that point. I noticed that between the first and second cylinder injectors that a rubber line that ran on top of the injectors appeared to have diesel around it and it was such that I could move the line easily on the fittings.

I came in the house and went to TBN and went to the Yanmar discussion page, and what to my surprise was a 17 page thread of "Yanmar loses power, slows and dies". Exactly what mine was doing with the exception that mine wouldn't stay running. After reading the 17 page of tallyho8's problems and related suggestions, I had a pretty good idea of how the fuel system worked. I learned that the top lines were return lines, and if the system sucked air anywhere that it would stop running. Based on what I read, I determined that the problem was probably air coming in where the line was loose. So I removed the line for inspection, found cracks and repalced it. Started up immediately and sounds as good as ever.

I will replace all the lines when I get done with my immediate projects, but want to thank everyone who spends their time assisting others here. I know that the informative posts take a lot of thought and time, anyway, "thumbs up" to all.

 

[Jimlitts]

TallyHo8, I have a John Deere 750 with a Yanmar diesel doing the same thing. I really liked your idea of putting in clear lines to try and track the fuel. I put in some plastic line but now can't get the tractor to start. I bled the lines clear to the injectors and still no luck. I have read that there is a certain amount of pressure needed to mist the fuel into the injectors and my thought is I'm not getting enough pressure through these lines to start. TallyHo8 did you have this issue and how did you get around it? Could this mean my injector pump is bad?? Been fighting this issue for 3 years and also took to shop. Thanks for any help!

 

[HoyeTractor]

I put in some plastic line but now can't get the tractor to start. I bled the lines clear to the injectors and still no luck.

The clear hose will only work between the tank and the pump. It is hard to tell from your post where you used the clear hose but if it is between the injectors and the pump it will not work. Those have to be very rigid steel. There will be over 4,000psi in those lines and any flexing will act like air and prevent the injectors from spraying.

 

[clemsonfor]

Yea Aaron, I was thinking get the same thing. You can't put plastic or rubber or whatever after the pump??

 

[Dieselbird]

Hey Guys, don't know if yall are still active on the forum but my account was finally activated so I can add my thoughts on this problem.

I have a john deere 1050 that has basically the same engine and fuel system as the OP's tractor and I have dealt with this same problem on and off since I got the thing in 2014. For years I thought it was the injectors or pump and about a year ago I took all that apart and cleaned them thoroughly and it seemed to help but it didn't last. I had found improvements by adding 2 stroke oil or peanut oil to my fuel. I noticed that it would only give me trouble on some tanks of fuel. I have ordered the fittings and clear fuel hose to add the OP's fix with the tees to allow the bubbles to go up to the tank return so that should fix it for good... However, I think I know where the bubbles are coming from.

My original idea was the fuel boiling in the injector lines, I tuned up my cooling system and it made the tractor run longer before having trouble. At this point I wondered if the bubbles were caused by crankcase pressure buildup leaking in somewhere on the back of the injector pump into the gravity pressure fuel supply. I plugged the crankcase vent and it didn't affect anything. Then I found this thread. I found that my tractor was indeed getting bubbles in the fuel line like the OP described. This is when I came to my current conclusion. I think that there is water or some other contaminant absorbed into the fuel and when the inside of the crankcase exceeds it's boiling point and heats the injector pump assembly I think that this contaminant is boiling out of the diesel fuel and creating the bubbles. I think this explains why I only have the issue on some fill ups.

I suppose this is the downfall of gravity feed returnless fuel systems.

Someone a long time ago in the thread suggested the fuel boiling but the idea was quickly shot down on the fact that the boiling point of diesel is "much higher than gasoline" I feel like it's definitely some other substance being carried along with the fuel that is boiling out.

Anyway, 10 years later but maybe someone who is having this problem will see this and it will help them understand.

 

[lackeym]

Had the same problem as tallyho8 is having and ended up being the fuel filter assembly. They have 4 ports on them, the 2 ports that are at a 90% angel are pressed in or something. The one on the left side moved a little and went to take the line off and it 90 came off the housing. Put a new assembly on works perfect. Hopes it helps

 

[kmartshopper]

New here ... hi I had a similar issue with my YM1700... running all day and shut down. Figured it was a fuel pump, so i swapped that, the filter, and the fuel line from the filter to the pump...

It will start to slowly bog out after running for a bit. The only way I can keep it alive is to loosen the banjo bolt and shake it ... if i leave it loose, it spills out plenty of fuel but the tractor will get power and run... Obviously this isnt a solution...

Doesnt matter if the banjo bolt holes are lined up to anything in particular, it doesnt want to function when tight... The washers on it are the same as before.. Ive tried removing the washers, or stacking them one way or another.. no dice..
Its not the fuel.. the sister YM2000 runs on the same juice and it runs like a top. Ive tried running it without a fuel cap ( i dont recommend) Weird... The next thing ill try is some other kind of banjo bolt to see if this one is just incompatible with the pump ( though its the same OEM pump replacement)

 

[bmaverick]

New here ... hi I had a similar issue with my YM1700... running all day and shut down. Figured it was a fuel pump, so i swapped that, the filter, and the fuel line from the filter to the pump...

It will start to slowly bog out after running for a bit. The only way I can keep it alive is to loosen the banjo bolt and shake it ... if i leave it loose, it spills out plenty of fuel but the tractor will get power and run... Obviously this isnt a solution...

Doesnt matter if the banjo bolt holes are lined up to anything in particular, it doesnt want to function when tight... The washers on it are the same as before.. Ive tried removing the washers, or stacking them one way or another.. no dice..
Its not the fuel.. the sister YM2000 runs on the same juice and it runs like a top. Ive tried running it without a fuel cap ( i dont recommend) Weird... The next thing ill try is some other kind of banjo bolt to see if this one is just incompatible with the pump ( though its the same OEM pump replacement)

The reason why I use Seafoam and/or Gumout Tune-Up. Whatever one is on sale at the time. The Gumout works a tad better overall. Diesel can have microbe build up in the fuel system. Even the metal fuel lines that can clog easily.

 

[ponytug]

New here ... hi I had a similar issue with my YM1700... running all day and shut down. Figured it was a fuel pump, so i swapped that, the filter, and the fuel line from the filter to the pump...

It will start to slowly bog out after running for a bit. The only way I can keep it alive is to loosen the banjo bolt and shake it ... if i leave it loose, it spills out plenty of fuel but the tractor will get power and run... Obviously this isnt a solution...

Doesnt matter if the banjo bolt holes are lined up to anything in particular, it doesnt want to function when tight... The washers on it are the same as before.. Ive tried removing the washers, or stacking them one way or another.. no dice..
It's not the fuel.. the sister YM2000 runs on the same juice and it runs like a top. Ive tried running it without a fuel cap ( i dont recommend) Weird... The next thing ill try is some other kind of banjo bolt to see if this one is just incompatible with the pump ( though its the same OEM pump replacement)

Welcome to TBN!

That sounds as if it is fuel starvation, but occasionally I've seen a clogged air intake cause almost the same symptoms. I would check the fuel line for an air leak, crack, or a piece of debris. You might need to get the entire line clean and dry, and look for a small weep. Did you check the tank for debris? Have you blown the line into the tank from the filter side?

+1 on a SeaFoam treatment. You can fill the fuel filter with it, run the engine briefly to get the SeaFoam into the injectors, and stop the engine to let it soak for a while (e.g. a day). I add the rest of the can to the fuel tank.

All the best,

Peter

 

[kmartshopper]

Thanks for the suggestion.. I think whats going to happen is that I'll bushhog with the wounded goat until I burn off enough diesel.. then I'll drain the rest... I'll give it a shot to replace the fuel feed line from the tank and the return line.. let's see how that goes.. as for the tank.. there's no contaminants in there and the fuel floods out when I remove the banjo. I'll check back once I've gotten a bit further

 

[ponytug]

@kmartshopper if you are going to go brush hog for awhile, I would add a can of SeaFoam to the tank now. It can't hurt, and may help.

All the best,

Peter

 

[kmartshopper]

So, i did replace the return line, and the tank to filter line.. pretty much everything is new now up to the injector hardlines from the pump. Of course i didn't tighten the banjo bolt and the topped off tank of red diesel decided to drain itself. I did get a new banjo bolt with a bleed screw from southern tractor. I also drilled out the return line at the tank for slightly improved flow.

Some folks are suggesting seafoam. that sounds great.. however thats not my problem.. the lines are clean. the tank is clean. So what happens is, the tractor will start to lose full power .. say about 1/2 then continue to drop in power. Ill lean over and loosen the fuel banjo bolt to the mechanical fuel pump.. ill shake the loose but still attached bolt, some fuel is spilling out but the tractor goes back to 100% power. if i tighten it,,, it will loose power as before. if i leave it semi loose, spittiing out fuel , it will stay at full power.

A may be a vacuum issue perhaps, but not from the tank,, ive run it with the tank with no cap and go through the same issues. The new pump might need calibration... ill have to dig into the manual and see if this is where im having issues... its possible that my fuel air mix is off, though i would suspect that it would be a factor from the moment i turn it on rather than over time.

Once i make it over to get some diesel, ill give her another run with the new lines and the new bleeder banjo.. If problems persist, its calibration time w the pump,. which i hear is not exciting

 

[kmartshopper]

Good news finally.. After a run for some off road diesel, she ran for about an hour.. at first it tried to bog, but i unscrewed the bleeder.. looks like there were some bubbles.. and not a problem after... i had to stop bush-hogging once the drizzle became down-pour and lightning... So, prob a combination of changing out the return line, boring out the return connector to the tank, the tank to filter hose and the new banjo bolt with the bleeder. I was on to something with shaking the banjo bolt around but prob wasnt getting rid of trapped air slowly making its way back up to the injectors.

I appreciate those that were helping with suggestions. Its good to have a good community that helps.