2004 Yukon 6.0 engine stall

[oldchev]

Hey gang...my 2004 Yukon Denali 6.0 stalled on restart. Drove it to location and upon start to go home it stumbled for 5 seconds then stalled. No restart but cranks fine. Acts like it might fire if i wait 10+seconds with key on then crank. I can hear FP relay click if i momentarily hit start (just tap the start switch) then let off to listen. This had a code P0171/0174 with MIL illuminated but went off last night after an agressive acceleration.
Drove to location fine no MIL light.
Waiting for tow truck.
Do you all think the fuel pump is quit? Can't check pressure until home.

 

[oldchev]

Part II...I got this home and as the tow truck was leaving I tried the start and Viola! it starts. I started it multiple times. After recovering from denial, I hooked up the fuel pressure gauge and with key on engine off, runs at 35 psi. When starting it levels off at 54 psi and constant. While engine running I pulled the FP relay and as pressure falls it didn't stall until near -0- psi. My take is the pump wasn't running at the location it stalled (above). My next thought is it may have very well been sporadic and quit momentarily but long enough to cause the P0171/0174 codes. I had been examining options for the DTC code it gave me.
My question is anyone having a similar experience with a sporadic fuel pump failure?

 

[Rivieraracing]

If and when it stalls out again and won't start, hit the bottom of the fuel tank hard with your hand a few times and see if the truck will start after that. Not saying that will tell you whether or not the fuel pump is on the way out but when mine went out it died on me and wouldn't start. Hit it a few times and started for about 10 seconds again and died for good! Just a thought!

 

[Rivieraracing]

Also looked up your codes!!! http://troubleshootmyvehicle.com/gm/4.3L-5.0L-5.7L/how-to-test-a-lean-condition-1

 

[oldchev]

Seems the fuel pump had an intermediate failure. As it might fail while driving the fuel pressure would drop yielding a low pressure delivery rate and producing the DTC P0171 and P0174 lean codes. Of course it was lean...it was about to die from fuel starvation! Then the pump would start running again for who knows how long until two days ago. Like I noted before after the tow truck left it started and ran fine.
I'm not a gambler so I pulled the fuel tank and removed the pump and installed a Delphi DFG0808. The original says BOSCH on it not AC Delco. Guess that's what they used then. At any rate I now have 55 psi constant. There is now 187,000 on this Yukon and runs great. In four + years I have fixed a lot of things, some small and some more intense but with the miles and age it a great vehicle. Maybe this experience will help someone else on the forum. Great site.