Yanmar loses power, slows down & kills

[tallyho8]

Tally,
Have you by any chance replaced ALL the rubber fuel lines ? Missing any copper washers from the banjo fittings to the injector pump? checked all the injectors for proper spray and that they are tight? Pulled the side door open on the injector pump & check that all looks ok while you move the throtle handle back & forth. finally, have you WAVED your magic japanese keychain we sent you over the engine, while burning incense and rocking out with Hendrix over the speakers?

1. Have replaced all the rubber fuel lines.
2. Don't know if washers are missing but it has been running fine for years and I never took it apart.
3. Will get injectors checked tomorrow. I am not qualified to check them.
4. With my limited knowledge of diesels I have been afraid to touch the injector pump.
5. I got the keychain because my diesel truck had so much tire trouble. I did the full routine with the magic keychain on my F250 and have had no trouble since. I forgot to do it on my Yannie. I should have done it before I dropped my boom box out of the fel and ran over it.

 

[rock2610D]

This is way off the wall but could your hydro pump be the cause?? Is it possible that in some way once the hydro system gets warmed the pump is dead heading somehow? Causing a big load on motor??

 

[YanmarFever]

This is way off the wall but could your hydro pump be the cause?? Is it possible that in some way once the hydro system gets warmed the pump is heading somehow? Causing a big load on motor??

This got me thinking

Tally next time you start the tractor keep the 3 point all the way down, dont lift it and see if it still dies on you.

I have a 1610 here that the 3 point lift handle was way out of line.
and when I would pull the handle ALL THE WAY back the tractor would bogg down instantly

dont hurt to try ?

 

[tallyho8]

Today I took my injectors out and brought them to an expert diesel repair shop, that does nothing but injectors and injector pumps. They checked them and said they were perfect. They were very helpful and explained a few things to me. They said my problem was most probably not injectors or injector pump especially since it usually starts so easy. They mentioned the fuel return line could do it and told me to go check if I had a return line on the injector pump that could be blocked. I don't have one after checking and my return lines on the injectors are off right now.

After the engine warms up, it will slow and kill if it is just sitting there on full throttle.

I took 3 videos that I am posting that may give someone an idea. They are of low quality. #1 is starting the engine and running it at different speeds before it warms up. #2 is the warm engine killing. #3 is restarting it after it kills only to have it kill again.

I have 2 more things I am going to go try right now then my wife better hide my hammers from me.

http://members.cox.net/tallyho/yanmar1.mpg
http://members.cox.net/tallyho/yanmar2.mpg
http://members.cox.net/tallyho/yanmar3.mpg

 

[tallyho8]

OK. Now I'm starting to get somewhere, but I don't know where. I have made a discovery. Let me explain the setup first.

I put a fuel can on my hood and ran a line straight down to the fitting on the bleeder valve on the injector pump. When the engine starts to kill, I open the bleeder valve and some fuel and air bubbles come out till the fuel runs clear then the engine picks up speed and runs better for a while then starts to kill again and I repeat the procedure.

It is impossible for air to get in the fuel line any kind of way with this setup.

The only conclusion that I can come to is that my injection pump is somehow bad and when it heats up it pumps some air backward into the fuel line.

Injector pumps are $$$$$$$. I hope someone comes up with a better idea.

 

[fonman_4859]

Tally don't know if this might help but I had a garden tractor with a plastic fuel tank that would start and die just like you are discribing. What I found on it was the nipple on the tank where the fuel line attaches had a crack around where it went into the tank. It didn't leak fuel but it would suck air when the engine was running, I think due to vibration. I got a repair kit to replace that nipple and have not had any trouble with the tractor since. Good luck.

 

[dieselgeek]

Videos sound like fuel starvation, not bad timing. I doubt it's the injector pump.

what about a collapsing fuel line? Saw this in a race car we worked on once, had a similar mystery issue where it ran fine for a few passes, then slowly fuel starved to stall. Let it sit a while, the cycle repeated itself.


I'd go through all the feeds and returns and make sure nothing is collapsing. In our case, the fuel line separated internally and a chunk would fold over and block the rest of the line. All while looking perfectly normal on the outside.

 

[kenmac]

sounds like (to me) it's just running out of fuel

 

[YanmarFever]

Tally, it sounds like you have a fuel starvation problem, what happens when you disconnect the fuel line to the injector pump and turn the key to crank it over , Does fuel come out of the hose?

If it does'nt I would replace the whole fuel filter unit

Or you have air leaking in to the system at the filter unit.

If you want I have one I can ship you to try out & see, if you ship it back when you're done.

I also have an 1802 here if you need me to compare anything.

Ernies Imports

 

[tallyho8]

Tally, it sounds like you have a fuel starvation problem, what happens when you disconnect the fuel line to the injector pump and turn the key to crank it over , Does fuel come out of the hose?
If it does'nt I would replace the whole fuel filter unit
Or you have air leaking in to the system at the filter unit.
If you want I have one I can ship you to try out & see, if you ship it back when you're done.
I also have an 1802 here if you need me to compare anything.
Ernies Imports

When I disconnect the fuel line at the injector pump, fuel flows out of the line until the tank is empty. It is gravity fed so I don't have to crank it over.

I have bypassed my tank, fuel filter and fuel lines by putting a lawn mower tank on top of my hood with a new fuel line running straight down to the injection pump and it does the same thing. Air is getting in the fuel line by the injector pump connection. When the engine starts to kill and I open the bleeder valve on the injector pump, a few bubbles come out and then the engine picks up speed again. I can not figure where this air is coming from if it is not backing out of the injector pump.

I wonder if the new hose fits tight enough and the hose clamps are tight enough, but the stock hose clamps on it don't seem like they have to be very tight for it to work.
I wonder if I take the hose off my fuel tank and pull a vacuum on it with my vacuum pump and see if it loses the vacuum. Or would pulling a vacuum on it damage my injector pump, or if the injector pump would even hold a vacuum.
I am running out of ideas and I appreciate all that you have given me.