96 12v cummins wont stay running...
 

Hello, let me start off by saying Ive owned this truck (1996 2500 12 valve cummins) for two months and I have never owned a diesel before. One day I went to leave work and with no prior signs my truck started up ran rough for a min or so then died. I changed my fuel filter and did not fill it with fuel first and used the primer button but nothing would pump into the filter. Finally I bought fuel and topped off the filter and reattached it, still wouldn't start. Had it towed home. Now at home Ive been fooling around with it and so far I have dropped the pre-filter and cleaned it out and put new fuel in it, put 4 gallons in my tank and removed the fuel filter and pumped the primer and now fuel comes out. So I put the filter back on and didn't tighten it all the way down and primed it until fuel spilled over then I tightened it back down primed the lift pump more and it fired up! However it only will run for a few mins then dies, I have repeated the process of cracking the fuel filter and letting air hiss out and re-priming and tightening it back down and then priming some more and it will fire up again, I have done this now 4 times and my little thumbs are killing me from priming so much. Any ideas of what could be going on?!?!?! Please any advice is helpful and thanks in advance. :argh:

Sounds like the diaphragm in your lift pump has had it. How many miles are on it?

Yeah low fuel pressure delivery, low volume ... does your oil smell like diesel ?? :humm:

Someone did mention that the diaphragm might be shot in the lift pump, haven't smelled my oil but i will check it out, also has 387xxx miles lol. One other thing I forgot to mention is while priming it a little bit of fuel leaks out around the primer button.

New lift pump and gaskets are $100. If there's any chance at all it's original, just do it.

I ordered a new lift pump and will start there. Any other advice out the, how hard is it to change that lift pump?

Depends on you're experience. Honestly, it's a royal PITA, but you can do it with basic hand tools and some patience. Obviously a lift makes it about 1,000x easier, but it isn't necessary, and it's still a PITA. My advice, (if it's 4WD) disconnect the front drive shaft from the pumpkin and swing it out of the way. Take out the starter. You can do it all from the bottom, but when you're trying to get all the holes lined up to install the new one between the bolts, pump flange, heater plate and two gaskets, you'll probably want more than one angle of attack to keep the stress down. In which case, you may want to remove the fuel filter too.

Does it matter if my pre heater electrical lines have corroded away from the heater part on the top of the pre filter? That's another thing I discovered while pulling and cleaning the pre filter. A diesel mechanic i know seems to think it will run fine without the wire harness hooked up to the pre filter.

It will, although it's good to have in the winter, especially up north. I can pretty much guarantee that isn't your problem though.

the wires can be fixed later .. or just Delete the Fuel Heater all together ..