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Fuel issues, need injector pump rebuilt......?

2K views 3 replies 4 participants last post by  JLanzino 
#1 · (Edited)
I'm bringing this over from the CUCV board on steelsoldiers.com
Truck is a 85 J code M1008 with 95xxx miles. Any help would be greatly appreciated.


I'm having some issues with my truck. If i drive my truck at a sustained speed over 45 or so it seems like its running out of fuel. It will kind of stumble and then catch itself and continue to do this until I slow down. When it does stumble I notice a small puff of black smoke though. I don't know if its overfueling causing the hiccup or if the pump catching back up is causing the smoke.... I replaced the fuel filter, checked for bad/worn lines, and put a new lift pump on it. It does it regardless of fuel tank level so its not the pick up. I pulled the return fitting of the top of the injector pump and it seemed to be stuck, so I played with it and got it to release and cleaned it the best I could. That made me think maybe it was getting to much fuel? Seems odd to say for a diesel. So now I think i'm looking at having the pump rebuild.

Any other ideas?

Is there anyone that you guys recommend to do this? Maybe someone near St. Louis that I could take the pump to. I really don't want to mess with the ebay crowd. Thanks
 
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#2 · (Edited)
The 85 still had the rubber governor flex ring in the IP that is known to fail. I just went through it myself. Pull the top of your IP off and look for what looks like coffee grounds in it. Mine did exactly what yours is doing right before it failed completely. If u have coffee grounds in the IP u need a rebuild on your pump. When rebuilding make sure they put an "eid " upgraded flex ring in it. If you go with a new pump make sure its either been updated or is from 86+.

Also if you do have the coffee grounds you can take your return fitting off and drill the check ball out. This will allow fuel through the return system and allow you to drive for a few days with the bad pump but it will need to be replaced.

If no coffee grounds it could he an air/fuel leak.

On a diesel overfueling means racing engine....the black smoke means too much fuel to burn efficiently but not enough to cause an engine racing symptom. Puffs of smoke are normal under hard acceleration.
 
#3 ·
I think Mike has you pointed in the right direction. Try using compressed air and blowing out the retuen line also (fuel cap off)

Something else to look at though. When You have a low power/black smoke condition it usually isn't overfueling but under airing. Enough air for light driving but not enough for heavy throttle. If no coffee grounds look for an obstruction in the air intake or something. Enough air for light driving but not enough for heavy throttle
 
#4 ·
Agreed
 
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