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JD 850 fuel problems

Marlin Booty I have a '88 850 that's been good to me since '92. It has 700 hours. This year it started stalling out. It runs fine for about 5 min. and dies. Sometimes it runs up and down between 1000 & 1500 rpm at full throttle for a while before shutting off. I've replaced the fuel filter, all the rubber fuel lines from the tank to the injector pump, the return lines on the injectors and the injectors.

Today I found it will start right back up for a min. or two if I bleed the injector pump.

The concensus with everyone I've talked with is that it wouldn't run if the pump is bad, so...what's left?

Dale G. Basgall Marlin :

I am basing this text on the assumption that this is an 850 compact utility tractor with a three cylinder yanmar engine in it and if this is the case here is what I have experienced with those.

Symptom 1= Engine runs fine and then intermittently starts loosing power and missing out nearly dying, when the load is taken off the engine and idled back it sometimes recovers and the reacts again, air bubbles evident in fuel system.

Rare is the possibility of one hanging injector, in the system if one injector happens to hang a little on a compression stroke air will be injected back into the injection line and back into the pum causing a missfire and then almost dying out. By simply bleeding the system it will run fine again for awhile.

Another problem I have experienced with those is a restricted fuel flow in the tank itself on the hose with the tank filter on it, simply blow low psi air back in the line as to backflush the fuel tank filter in the tank.

Another problem I have encountered on a 935 with the 3 cylinder yanmar is that the fuel hose inside the tank could be deteriated in the event that unit does have rubber lines inside the tank, I am taking that scenario of bubbles in the fuel pump and system, you may actually not have the rubber lines inside your tank.


Marlin Booty Dale
Thanks for the input. I have had to blow out the fuel line from the filter back to the tank and that's one line I replaced. I think I'm going to drain the tank and try cleaning it out. I don't know if there's rubber hose inside. Guess I'll find out soon enough.

Dave Smith I have a similar problem . I have a 2305 john deere and it started dying out while cutting grass with the mid mower. It would start right back up and go a few moree minutes and do the same thing. When not under load it simple loses rpms and the goes back up. I changed the fuel filter which had some crap in it but it still does the same thing. I read here that there is a filter in the fuel tank that can get plugged up. Is it replaceable? or do you just blow it out. If you blow it out the crap just goes back into the tank.... Is ther an easy way to clean out the tank of any crap?

Thanks for any help you can give as I can't afford to take it to a dealer.

Dave Smith

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