Chevy Impala 2004 gas problem
 

All started when I replaced the FPR, Car will take forever to start but when it starts it runs fine minus acceleration. If you shut it off and try to turn it back on within 30 minutes, starts up perfectly.

Been driving on it like this for a year no problem. I don't suspect the pump. If you pop the vacuum off the FPR it doesn't change the idle in the engine.

5 PSI when key cycling, 25 PSI when running. Should be between 53-59.

Going to try a new FPR this weekend, however, if it's not this what should I check for next? It's getting a new pump if this **** doesn't work.

3.4 2004 Chevy Impala Base Model.

Lean Fuel Engine Bank 1, Max adapt long shift, Massive EVAP leak, and a few I can't remember.

Sounds like it could be a bad check valve in the fuel pump. It is letting the gas drain back into the tank and has to re-prime itself after sitting.

I had a bad FPR on my Pontiac. I remember going through the troubleshooting with it. When running the fuel pressure was low like yours. When shutting off the engine, the fuel pressure would drop to 0 almost instantly. It was supposed to drop less that something like10-20 in a minute after shutoff. The test to determine where the leakage was to plug or crimp the fuel return line out of the FPR to see if that made a change. I was getting fuel rich errors which I never understood why, other than maybe with the lower pressure the fuel wasn't spraying out of the injectors properly and coming out like a stream instead and not burning right.

you need to deadhead the fuel pump briefly. this will tell you if the pump can develop the pressure its suppose to or you have a fpr problem