Hey everyone - I am a regular lurker and archive searcher, but I was thinking it was about time to make a post and say Hi! And I have a problem to solve too

I have been working on a re-power project for the last year or so - putting a 1st gen Cummins into my 75 Power Wagon. I'll try to get some pics up soon for those interested.

For the most part everything has been going well until the fuel that has been in the tanks for the last six months went south on me. Just for the record it had some B20 in it.

The truck has not been driven regularly at all, however the engine is started regularly for testing and it has made a few laps around the parking lot across the street... So last week when I started it up, it had an erratic idle that kept getting worse by the minute. Figuring the fuel might be bad, I drained the tanks and refilled with straight fresh diesel. It still ran with an erratic idle - almost runaway on startup - I investigated further finding a brown sludge that smells like polyurethane or turpentine jamming up the fuel filter and pretty much everything else.

Most likely scenario is that condensation in the tank contributed to some growth in the tank and now the whole fuel system was contaminated with the resulting goo... So I treated the tanks, flushed the lines, and ran a few bottles of Diesel Purge through the engine.

The current situation is this: The engine starts and runs but the idle is notably low. If you blip the throttle the idle goes to a more normal level. It will stay there by itself, but if you put a load on the engine it drops back down and stays there. You can blip the throttle and it will come back up. The truck will move under it's own power, but it seems to lack the punch that it should have - i.e. low on power.

The question is, what should I do now? Is something in the injector pump still gummed up and stuck? I have replaced the fuel filter and the lift pump is less than a year old.

Thanks in advance!
Fred

 

I would put a double dose of fuel system cleaner (Stanadyne, Howe's, etc.) in and work it as hard as you can. If you have a trailer you can haul around that would be good. Like you say, there's probably gummy goo everywhere inside, and the faster you can get that flushed out the better.

 

You can also run a can of Sea Foam through it. That stuff cleans fuel systems really good.

 

Thanks guys! Is the advance mechanism in the pump bathed in fuel? If that's the case, I'll bet you that's what might be gunked up.

I'll run another dose of the additives through and then give it a good long pull as suggested. I better get the windshield in!

 

The whole inside of the pump has fuel flowing through it. Everything in there probably has a layer of sticky goo.