Oil & Fuel S-470 D starts, runs for a couple of minutes, then slows and dies.

tomjae · Sep 15, 2014

I have a Mitsubishi Satoh S 470 D buck. I recently ran it out of fuel and had to bleed the air out of the fuel system to get it to start. It now starts crisply when it is cold, but runs for a few minutes or so and then slowly dies. Prior to running it out of fuel, it was running very well and had plenty of power. I bled the air as the manual says to, but I think I still have air trapped in the injector pump somewhere. Other than loosening the nuts on the injectors, and the bleed screws on the bowl and the inlet to the pump, is there something else I need to bleed to restore my power?

oliver28472 · Sep 15, 2014

If it starts and runs a couple of minutes you shouldn't have to worry about the nuts on the injectors. Check your fuel filter and the fuel cap. If you still have the original style filter setup, the filter at NAPA is 3264. The cap should be vented. Also there could be some type of blockage in the tank.

tomjae · Sep 16, 2014

oliver28472 said:
If it starts and runs a couple of minutes you shouldn't have to worry about the nuts on the injectors. Check your fuel filter and the fuel cap. If you still have the original style filter setup, the filter at NAPA is 3264. The cap should be vented. Also there could be some type of blockage in the tank.

Oliver28472 Thanks for the reply. I have changed the fuel filter. So far as I know, the fuel tank cap is the original. There is a screen wire cup on the fuel tank inlet and that is clean. I know that when I loosen the bleed screw on the bowl, if the valve is in run position, the fuel streams out, but I have not tried that after it warms up and ceases to run. Do you recommend draining the fuel tank completely and rinsing it out?

oliver28472 · Sep 16, 2014

That might be your best bet. You could be getting enough fuel to get it primed, then when it starts there's not enough to keep it running.

tomjae · Sep 16, 2014

oliver28472 said:
That might be your best bet. You could be getting enough fuel to get it primed, then when it starts there's not enough to keep it running.

Yes, that is what I think is happening. I will place funnel under the bowl with a coffee filter in it and then open the valve on the bowl. If stops, I will have my answer. I was concerned that there might be place in the injector pump where air could be trapped in a high spot such that when it heats up, the air expands and cause the pump to cavitate. The tractor was on a slight incline (the ground under the front wheels was about 5 inches higher than the ground under the rear wheels.

Ilikeurtractor · Sep 17, 2014

I had a problem once where one of my newly purchased diesels had the wrong fuel (I think it was gas, the previous owner claimed it was jet fuel - certainly not #2 diesel). The engine would run fine when cold, but would die when warm, presumably due to a lighter fuel vaporizing in the pump when it got hot. Probably not your issue but something to keep in mind.

tomjae · Sep 21, 2014

Ilikeurtractor said:
I had a problem once where one of my newly purchased diesels had the wrong fuel (I think it was gas, the previous owner claimed it was jet fuel - certainly not #2 diesel). The engine would run fine when cold, but would die when warm, presumably due to a lighter fuel vaporizing in the pump when it got hot. Probably not your issue but something to keep in mind.

Many thanks to Ilikeyrtractor and Oliver28472 for their suggestions. I drained the fuel from my S-470 D, blew out the fuel tank, replaced the fuel filter and re-filled it with fresh diesel. After a seconds of rough running, it returned to its old self. I don't know what else besides diesel was in the fuel, but when good, fresh diesel was in the tank, in restored the performance I lost. I hope I can help you guys sometime.