Duramax Losing Prime!!!

[K50]

Hey guys, I know this is a fairly common problem, but what the heck gives???
I just changed my fuel filter, no leaks anywhere, had the whole fuel system inspected 3000miles ago and they said it was perfectly fine, didn't throw any codes. I just picked up a Bully Dog tuner from GRI that I haven't had a chance to try yet, so I'll check for codes when I can, but does anyone know WHY they lose their prime? Where are potential problem areas? After pumping the fuel pump a couple times, it fires right up...
I let it sit for 4 days and it wouldn't start, had no pressure, I had to pump the manual pump until it was firm for it to start. Could it just be a cold weather fuel issue?


Thanks for any tips

---AutoMerged DoublePost---

hmm... I'm thinking - it's not tight enough or I didn't tighten the bleeder screw enough, or it's the crap fuel that's in my tank right now or a combo of both.... Maybe something came loose after I installed the new filter..

[2500HeavyDuty]

the filter and the bleed screw should be hand/finger tight and it should be fine. How cold is ti up there?

[cbrew2001]

I just had to have my water sensor replaced on the bottom of the fuel filter. The bleed (drain) valve just started leaking (dripping) diesel and the valve has never been opened. It started losing its prime slowly and with a very slow drip out the valve.

[2500HeavyDuty]

all them stuff can be hand tight, the wif sensor can be wrenched on, but not too tight

[wtfd6]

An easy way I have found to see where fuel is bleeding off is to take a piece of clear hose about 7ft long and connect it to the inlet of the cp3 and to the hose connected to it. This way it is inline and just hang it from the hood. See which side leaks fuel down. That will tell you which way the fuel is going. That will help figure out where to start looking.

[redneckbuckeye]

Originally Posted by cbrew2001 I just had to have my water sensor replaced on the bottom of the fuel filter. The bleed (drain) valve just started leaking (dripping) diesel and the valve has never been opened. It started losing its prime slowly and with a very slow drip out the valve.

I had to do this also, truck kept losing prime.

[cbrew2001]

Fixed now though, I must have bumped it or messed it up on the last fuel filter change.

[K50]

Well, this weekend my truck seems to have been running better, but I'm wondering if the WIF sensor as Danny mentioned might be starting to develop a mild leak. I ran all weekend with no more issues, but thanks for all the tips guys.

[2500HeavyDuty]

the wif sensor does use an o-ring to seal it up