Just got a new starter installed on my D20A-6 and was ready to get some overdue work done. But after about an hour of pushing dirt, it started sputtering and almost died on me with the throttle cracked a good bit. I had to limp it back to the house, letting it sit and speed back up a bit before driving a bit farther. It had been sitting up about a year, so I thought it's probably water in the fuel, or something got stopped up. When I cranked it up the next day to move it close to the shop, it ran just fine, so I eased down to the closest place I could work and started pushing dirt again. It didn't last for 5 or 10 minutes and started sputtering again. So I parked it by the shop and started troubleshooting.
First, I replaced the fuel filter. Then I pulled the strainer out of the fuel tank inlet and looked into the tank with a flashlight. I could see a little dirt in the bottom of the tank, and a nodule of some kind laying in the bottom as well. I didn't see any water, and everything I saw was well below the pickup tube. But I drained the tank and sucked out what was left anyway. I poured a few gallons of fresh diesel in, cranked it up and let it run at medium speed for a few minutes. It wasn't long before it started sputtering again.
So I moved up to the feed/injector pump system. I pulled the inlet hose off the feed pump, and fuel came running out, so I know that hose is clear. I pulled off the hose from there to the fuel filter, and from the fuel filter to the injector pump and made sure they were all flowing freely. I pulled off the priming pump, and the plug, spring, and piston in the side of the feed pump assembly and found no dirt or anything that looked bad. I blew air through the fuel filter assembly and it was clear.
Now I'm baffled. It runs like a champ, smooth as can be when first started, but after a short, random time, it starts sputtering and almost dies. I am not a diesel mechanic, and until 2010, never owned a diesel. So I have no experience troubleshooting the fuel system for a diesel. My thoughts right now are that the feed pump is not pumping fast enough to keep up with the demand at higher rpm, and after the fuel filter drains what fuel it has in it, the injectors are starved. But that is just a wild guess. I feel like the injector pump itself is working fine, but is starved for fuel.
I would appreciate any thoughts or opinions you may have on this problem. I am not scared to tear into anything as long as it is advisable. I just don't want to go removing something that is virtually impossible to replace after examining.
