Fuel pressure drops with key off.

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Rgrkck71

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Hello all, having an hard starting issue 05 Tahoe Z71. Checked fuel pressure, drops rapidly. Disconnected fuel line to rail, still drops. Figured fuel pump since it's never been replaced and live in Minnesota. Replaced fuel pump with Delphi Fg0808, surprised anything was working with how corroded everything was. Also replaced half of fuel line. Thinking I solved the problem and after test driving, the very next start having same issue. Pulled injector rail, nothing leaking. I'm now frustrated and lost.
Could I have gotten bad fuel pump? Can I have a leak without smelling or seeing gas? Any ideas greatly appreciated. Ty!
 

Scottydoggs

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was the old fuel line rusty inside? might have pushed crap into the injectors.

fp is going to drop after the key is off. the pump is off. what matters is the fp when you turn the key to run.
 

Sam Harris

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Agree. If the line was badly corroded, I’d expect you have some foreign material in the injectors, or places it shouldn’t be. Definitely need to see what the pressure is with a manual gauge.
 

Fless

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So if you used the Delphi FG0808 pump you must not have a Flex Fuel vehicle; if it is FF that's the wrong pump.

As several other posters noted you may want to get some definitive fuel pressure readings. Rent a fuel pressure gauge from your local auto parts store and test it at the fuel rail. Key on, engine off (KOEO). Document the fuel pressure, also note how long and to what pressure it leaks down, both with the key on and after you turn the key off. Get numbers.
 

Joseph Garcia

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Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.
 
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