Symptom:
The lift pump primes the system to 13-14 psi when the key is turned on then drops back to zero as normal however, when the truck is started, especially in the morning when cold, the truck starts and I get 0 pressure. I turn off the truck, tic the starter to get the pump to run, then start the truck and I have pressure for the run.

Now normally, I would suspect the lift pump is failing, however after my last fix, I think ANYTHING is possible! Who would of thought wrapping an alternator wire in tin foil would solve a transmission issue???

Anyways, Any ideas? Is the pump failing after 70k or is there some sensor or computerized gadget telling the pump to just sit there and drive me nutz! Is it related to my last issue? Or Am I just losing my mind?

I'm at a loss! I don't want to start buying parts just to find out I coulda said some magic incantation to make the problem go away! HALP!

 

do you have a needle valve in the line? try to open it more. could have vibrated shut. BUT, my guess is a really weak lp. your ecm tells the lp to run, I havent ever heard of it not doing that job, you could run a hot wire down to the lp to check, but I still say bad lp

 

But don't they tend to weaken before they fail? This seems to be reacting more of an electrical issue than a mechanical one. Because when I do get the pump to work it seems to operate at or near the normal pressures.

Also I 'm running a mechanical guage. no sending unit or needle valve. I didn't see anything that would make me think it is a guage issue.

 

Not having the needle valve could be a source of the problem. The needle valve acts as a 'snubber' in the system to smooth out the pressure spikes. Perhaps the gauge took a spike and was damaged?

 

I would agree but ..... the fact that I don't hear the pump trying at all tends to lead me to believe it is something telling it NOT to work rather than a failure or a guage issue. But.. then again..... who knows....

 

You should only hear the pump for a couple seconds when you turn the key to the "ON" position. The pump doesn't run continually until the starter is engaged.

 

If you just bump the starter but don't start it, how long does the lift pump run?

Mine doesn't run at all unless I bump the starter, then it will run about 15-20 seconds.

And they fail with much less than 70K.

You could have a failing LP. Sounds like your gauge setup is fine to me. A valve will do nothing to control pressure spikes, a needle valve can only control flow...not pressure, that's what pressure regulators do.

 

Had a Glacier Walbro Performance installed yesterday. Went with that particular one because you leave the factory lift pump in, and if the Walbro failed, you just switch one power plug and your factory pump is back on line. I was there and helped, and if you haven't seen it, you would not believe how frail looking and seems like 90% of it is plastic. Go to www.glacierdeiselpower.com and read the article "Factory Lift Pump exposed" great article and great pics.

 

That would be www.glacierdieselpower.com

I before E except after C! And except for the word "Glacier!"

<edit> That was good reading. Thanks for the post!

 

I have a new Cummins lift pump $55 Shipped to the lower 48 #4932707

 

Well I will tell you this, you decribed my scenario exactly. I bought a Glacier Diesel Performance pump in the summer of 06 and then this winter I had the exact issue you had, check my posts, and I actually ended up having to plop down 1900$ for a new injection pump. I dont know if it was the GDP pump i bought or what, but i bought the pump for the very reason of saving my VP44 and I ended up buying a new pump and VP44, so I dont know, sorta feel like the GDP pump caused all my issues, but I cant prove it.
Bottom line I think you need a new injection pump.

my .02

trout