Fuel Pump Chk valve

[stagrlee]

Got 210K miles on my '04 Tahoe. Truck needs its 4th pump. Pump pressure is fine but after you cut the engine the fuel pressure bleeds off rapidly. What the hell is going on with these AC Delco pump check valves??? I'm getting about 30-75k miles before they let go. Haven't been stranded as the pump keeps pumping, just the weird no start 1st try problem...

 

[OR VietVet]

Are you 100% sure you don't have a leak/bleed off spot elsewhere in the fuel delivery system?

 

[Scottydoggs]

if you dont have a visible or smell able leak. id suspect a injector is stuck open.

check fuel trims, see if one side is richer then the other.

 

[stagrlee]

Is there a good recommended spot to pinch the return fuel line in these trucks and repeat a bleed down test? Last two failures replacing the pump fixed the issue. Injector set has 55k miles on them. I replaced the injectors at 155K miles since I was doing the intake gasket at the time.

 

[ivin74]

if id suspect a injector is stuck open.

I agree w scottydoggs
Remove each spark plug and check if they are wet. If you find any wet ones chances are the injectors are bad.

 

[Wylie_Tahoe]

You could probably pop the injector rail up faster then remove plugs.

Dry each injector with a rag, place a paper towel under them, energize the pump and see if a wet spot forms.

You can pinch the return line anywhere its rubber. Just make sure its actually rubber and not a foam insulated plastic line.

 

[stagrlee]

So I pulled the fuel rail with injectors up and pressurized the system and the freaking thing is now holding pressure. Reassembled and is still holding pressure. Makes me think you guys are right and its a flakey injector as the last two times it was always consistently quick drain to no pressure. This time when its failing, its almost immediate drain to no pressure.

 

[Splorg]

I encountered something sort of similar, but intermittent, with a bad purge solenoid. It would start sometimes, other times you had to crank for a few seconds, then again, then it would catch. That would absolutely set your SES light, though.

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