1987 M998 Fuel Pump Help

1987 M998 Cargo\troop Humvee
Guys I have a strange issue. 2 months ago my Mechanical Fuel pump went out (the one mounted to the block to provide fuel to the injector pump). I ordered one from Ebay for like $27;00 and replaced it. Everything was fine and then last week no fuel again. I assumed it was because I purchased a cheap chinesiam pump. I found a NOS Military pump and ordered it to replace again. The interesting thing is when I pulled the pump off it was FULL of red oil. I have been adding Marvel Mystery oil to the tank on each fill up. Why in the world would the Marvel Mystery oil pool up in the mechanical fuel pump? I have not added an excess! Is it bad to run the Marvel oil in the Humvee? Maybe that is what killed the first OEM pump? Any ideas?

Did you get red off road diesel somewhere?

No it is THICKER than fuel, like transmission fluid consistency. Really strange, has me shaking my head. How in the world could trans fluid get into the mechanical fuel pump? The known vampire effect would not effect the fuel pump right? Just the transfer case and hubs right?

Did your pump have a chassis vent line connected? If so maybe you have vampire syndrome.

NDT said:

Did your pump have a chassis vent line connected? If so maybe you have vampire syndrome.

Click to expand...

Yes I think I have the Vampire issue, ugggg. Oh well time to get dirty.

You might just have the diesel bug if it is gooo ie. Maybe or not. Keep an open mind. See my posts to what might be the problem. Search others too.


This could be a very sticky mess, CAMO

I would change your oil & filter plus verify your transmission fluid level.

Did the red fluid come out of the vent side or diesel side of the pump?
You should check the transfer case first to see if it is over full, you should also check the diffs and hubs, it does sound like you are pumping trans fluid into the vent system, via an over full transfer case.

Algae in fuel looks some what red.....if it is...its in everything and must be cleaned out....tank to Inj. pump.

It is without a doubt the vampire issue. Going to bypass the transfer case and change all the fluids. Fun fun!