Oil & Fuel Need some help!! 4300 stalling!!!

PGDiesel · May 22, 2011

Hey guys!! New poster here and I need a little technical help!! I changed the fuel filter in my JD 4300 hydrostat last week for the first time... Tractor ran GREAT before the change. However, I almost never got the tractor to start after the change!! Now, the tractor will start but runs extremely rough. As I put it in gear, it may move 10 ft, and then cut off... as if it is losing fuel.

Do I have air in my diesel lines? How do I get this out? I have tried letting it run to try and get the air out, but the engine will stall out almost to the point of dying, then get a burst of fuel and shoot up to about 1800 rpms. Then, die back down, and shoot back up again. If I try to engage PTO or drive the tractor, the engine will die... Any thoughts?? Again, it ran great without any problems prior to this fuel filter change... So much for preventive maintenance!!!

kebo · May 22, 2011

Sounds like you already figured it out.... could still be some air in the lines. At least, changing the fuel filter was the only thing done to the motor before the problem started.

You will need to spin the motor over and crack open the lines to the injectors one at a time, just enough to bleed the air out of each one. The repair manual will tell you the exact procedure, if you have it.

PGDiesel · May 22, 2011

Thanks Kebo...

I will give this a try... Unfortunately, I do not have the repair manual, only the owner's manual. Should I open the three lines (hard lines) going directly into the pump (ie, at the top of the injectors)? Do I loosen them until fuel flows out?

Your help is greatly appreciated!!!:thumbsup:

kennyd · May 23, 2011

This systems are self-bleeding, I am betting the seal on the filter or bowl is missing, damaged or leaking and it's sucking air.

BRBurns · May 23, 2011

Could the fuel shut off valve not opened all the way back up and is choking fuel? I'd pull the filter out and inspect what you have going on.

Egon · May 23, 2011

Do you see a little lever by the fuel filter? If so start pumping it till it gets hard to move.

BRBurns · May 23, 2011

Egon said:
Do you see a little lever by the fuel filter? If so start pumping it till it gets hard to move.

I don't think the 4300 has this. At least I didn't see it on mine when I changed the filter a few weeks ago. Just had to start it a few dozen times to get the fuel back into the injectors.

PGDiesel · May 23, 2011

Thanks guys... Good info here. Actually, I called the local JD store and asked them a couple questions about my problem.

My tractor does have the lever on the side of the fuel pump. According to the JD tech, some of those tractors had a lever, while most did not. (evidently there was a design change around this time) I pumped this lever about 50 times without much success. Interestingly, on the first pump, it feels like it is pushing fuel through the pump, but there is little to no pressure on successive pumps. The tech told me to pump that lever and to just keep running the engine to get the air out of the lines. It would run rough for a while, but would smooth out after about 30/45 mins. May just be me, but it doesn't sound healthy to do that!!

I have checked the fuel shutoff valve and it is in a vertical (open) position. I do have a fuel leak on the petcock at the bottom of the fuel tank, but I doubt this would cause issues getting air into the fuel lines. I am replacing the petcock today.

I'll open the filter/sediment bowl back up to make sure it is sealed... then loosen the hard lines around the injectors to bleed any excess air. This is supposed to be a self-bleed system, so I am a bit stumped...

Thanks again for all the help!!