Fuel pressure issue? Someone chime in

Byoung1330

Full Access Member
Joined
Aug 26, 2018
Posts
401
Reaction score
206
Location
Cookeville tn
I have a 04 tahoe 5.3 flex. Changed fuel pump out about a year ago. Twice first one had bad check valve. Anyway I was bored today an put pressure gauge on to check psi. Well every video I see they pull fuel pump relay let it run out then hit Schrader with screw driver an relieve pressure. Well mine won’t stop. When I hit Schrader with screw driver it won’t stop coming out til I stop. No fuel at vacumn line to fpr. Also when running fuel pressure jumps up when I pull vacuum line to fpr so I’m guessing it’s ok. Anyone else ever seen this or is this normal ?
 

Fless

Supporting Member
Joined
Apr 2, 2017
Posts
4,568
Reaction score
7,667
Location
Elev 5,280
No need to relieve the pressure to test it. Just use a gauge on the schrader valve on the fuel rail. Key on, engine off, and that's how it's measured. I don't have the Flex specs handy but they're a little lower than non-Flex. I can find them if you need them, they're in an older post.

I don't believe you can get an OE fuel pump for these, but you should be able to get an AC Delco Pro / Gold version, which is what I have put in mine. ACDELCO MU2294 {#19337978} for Flex.

What brand of pumps are you using?

EDIT: PSI specs in this thread: https://www.tahoeyukonforum.com/threads/another-p0300-thread.128094/post-1591935
 
Last edited:

Byoung1330

Full Access Member
Joined
Aug 26, 2018
Posts
401
Reaction score
206
Location
Cookeville tn
Yes I know the specs. And I know how to connect to fuel rail done did all that. I just hate how it sprays out. An like I said all the videos I watched they hit the valve an it sprays an stops. Mine don’t it will keep dumping. My fuel spec was in pressure. It’s 48 to 54. Mine was about 50. I used a o Reilly’s pump can’t remember what brand.
 

Byoung1330

Full Access Member
Joined
Aug 26, 2018
Posts
401
Reaction score
206
Location
Cookeville tn
Just to confirm, you're starting the vehicle and then pulling the FP relay? The truck then dies and you attempt to relieve the pressure but it won't stop dumping fuel?
Lol yes. How else would I run it out. I’ve built my Tahoe from ground up. I know there a lot of dumb ppl out there that do dumb stuff. But I was Jw if there was a issue or if it was normal. Yes I run it out. Then try to crank a few times an when I hit Schrader it won’t stop. Just keeps pumping out gas. That normal?
 

RED TAHOE LS

Full Access Member
Joined
Jan 2, 2017
Posts
760
Reaction score
384
Location
Rossville, Georgia USA
I have a 04 tahoe 5.3 flex. Changed fuel pump out about a year ago. Twice first one had bad check valve. Anyway I was bored today an put pressure gauge on to check psi. Well every video I see they pull fuel pump relay let it run out then hit Schrader with screw driver an relieve pressure. Well mine won’t stop. When I hit Schrader with screw driver it won’t stop coming out til I stop. No fuel at vacumn line to fpr. Also when running fuel pressure jumps up when I pull vacuum line to fpr so I’m guessing it’s ok. Anyone else ever seen this or is this normal ?
Do as fless suggested.......put a fuel pressure gauge on the schrader valve, that's all that's important.
 

Attachments

  • Tahoe-1.png
    Tahoe-1.png
    196.6 KB · Views: 1

mattbta

Full Access Member
Joined
Jun 19, 2012
Posts
421
Reaction score
435
Location
Frisco, TX
Lol yes. How else would I run it out. I’ve built my Tahoe from ground up. I know there a lot of dumb ppl out there that do dumb stuff. But I was Jw if there was a issue or if it was normal. Yes I run it out. Then try to crank a few times an when I hit Schrader it won’t stop. Just keeps pumping out gas. That normal?
I was just clarifying, because I'm dumb and didn't fully understand what "run it out" meant.

My 2004 flex will spill out a little after pulling the FP relay and running it out, but it's not much and a single paper towel is enough to catch it. Based on that, I do not think your situation is normal.
 

exp500

Full Access Member
Joined
May 14, 2017
Posts
1,140
Reaction score
829
First time I put Fuel pump tester drain hose in small bucket and could not stop the siphon till closed drain and air gapped hose. If thats what I wanted it would never work- ask Murphy.
 

Byoung1330

Full Access Member
Joined
Aug 26, 2018
Posts
401
Reaction score
206
Location
Cookeville tn
Do as fless suggested.......put a fuel pressure gauge on the schrader valve, that's all that's important.
Yes I done that lol. I got my pressure reading. It read in spec. Was just a simple question of why the pressure does not bleed off or relieve. Was wondering if that’s some kind of issue with something else like something to do with any kind of evap stuff or anything Like that.
 

Forum statistics

Threads
114,490
Posts
1,561,045
Members
73,156
Latest member
Giovanell88
Top