What gives????

[c23380]

My uncle has a ford 860 and has been complaining that it will run good just putting around but when you work it, IE plow,mow with rotary or finnish, it will start running rough and quit after 3 to sometimes 20 minutes. It will restart but will not run @ pto speed for a few minutes. I sound like it is starving fuel, but I am not positive. I have checked the line from the tank, replaced it's filter inside. Pulled the bowl off while it is running rough, and verified there is fuel there, (no vapor lock). I have also replaced points and condensor, adjusted fuel mixture. I have disassymbled the carb, and inspected it. No faults found. I also adjusted the float a little, to ensure more gas in bowl. I have exausted all I can think of. Any other ideas??

 

[Hooked_on_HP]

Possibly the ignition coil .
Bill

 

[jinman]

It sounds to me like a classic case of fuel vaporlock or fuel boiling. Electrical problems don't usually come and go that quickly and when they happen, it normally is an all or nothing situation. It would not restart and run rough. An electrical problem can cause a tractor to run rough under load, but it would not wait for 20 minutes to do that. It would do it all the time. For electrical problems, I like to start the engine after dark, put it under load, and look for jumping sparks around the wires or distributor cap. I guess you could have problems with the flyweights in the distributor hanging up and not adjusting the timing advance, but that is a remote possibility at best.

This just sounds like a fuel problem to me. Is there some way to shield the fuel lines from heat? Has the tractor had any heat shields removed? Can you put ice on the carb or fuel lines to cool them when the tractor is running rough?

One other thing. . . how old is the gas? Can you drain the gas and put in all fresh fuel? It might be just a bad tank of gas if it just developed this problem recently.

 

[Hematite]

I would guess that you got a tank of bad gas with water contamination? Don't see that much anymore with 10% Ethanol gas, though.

Another possibility is a weak ignition coil or an improperly wired coil. Check to see that the wires are going to the correct terminals on the coil. Improper polarity coil hookup will eventually kill a coil.

 

[Maknwine]

Have you checked to see how clean the air cleaner assembly is? A clogged air filter makes for running like crap issues too.

Good luck
Tom

 

[c23380]

Thanks for the advise guys. I have cleaned the aircleaner and the other things mentioned but I have not looked into the coil possibly being the issue. I will swap it out with his 900 and see if that makes any difference. Thanks all

 

[c23380]

Also Jim, I was not ignoring your input. I have replaced the gas and as for the fuel lines, I know the old fuel line comming from the tank was copper and it does run neer the exaust manifold. He has replaced it with steal. Still it is no closer to the maifold than it ever was. Do you think changing from copper to steal would make a difference?

 

[jinman]

Also Jim, I was not ignoring your input. I have replaced the gas and as for the fuel lines, I know the old fuel line comming from the tank was copper and it does run neer the exaust manifold. He has replaced it with steal. Still it is no closer to the maifold than it ever was. Do you think changing from copper to steal would make a difference?

I wouldn't think changing from copper to steel would make that much difference, but I'm no expert. I'd think if he changed from rubber fuel line to metal, it could make a huge difference. Normally, there is enough air flowing back from the engine fan to move the really hot air away from the fuel lines. Has he put anything in the way of the cooling air?

I guess you could put aluminum foil between the exhaust manifold and the fuel line to see if that helped. The danger of that is that it will take a lot longer for the fuel line to get hot, but once the line gets hot, the foil tends to hold the heat in as well. If you tried it and it delayed the onset of rough running for a significant amount of time, at least you would know where your problem is and start looking for a fix like a permanent heat shield.

I think the content of fuel has changed so much since that tractor was new that there is a possibility that the boiling point of today's fuels might be less than the old leaded gas of that tractor's era. If I'm wrong, and there's a TBN expert on this, please correct me. The thing that would keep me looking at fuel is that the tractor seems to run rough after getting hot and then returns to normal operation when it cools off. If it were an electrical problem, I'd expect it to just die like you turned off the key when it gets hot and then restart when it cools down. That could be caused by a heat related short or open inside the coil, but I think it would be instantaneous all or nothing instead of rough running and no power. I think the problem is mechanical or fuel related, not electrical.

 

[Carykong]

maybe I missed your trouble shoot description. you checked fuel flow from tank to inline filter,yes? did you check fuel flow at the carb?

 

[jinman]

This thread sure sounds similar.

Stalling 800 Series