1999 Pontiac Grand Prix GTP 3800 SC

Reader Question: Hello,

I have a question about a 1999 Pontiac Grand Prix GTP 3800 SC. The car will stall at times at idle. The fuel pump comes on for 3 second every time without fail when the ign.switch turns on but does not come back on after the engine starts.

I attached a pressure gauge on the fuel rail. The pump builds pressure every time at 45 PSI. If the car is cranked it will run until the pressure drops to below 10-0 PSI or so as the pump is off.

Once the engine stalls, the pump will come on and build to normal pressure. Could this be related to the pressure regulator? I have switched the relay with another identical relay next to it. Both seem to work fine. I also scanned for trouble codes… none.

I have several ideas but hope that you may have seen this problem before.

Thank You.

Micah

Hey Micah,

I have not seen this particular problem before. I would double check that you have power to the fuel pump when the engine quits running.

If you do have power to the pump and it is not working, you would need a new fuel pump. If you do not have power to the fuel pump then I would double check the power from the fuel pump relay, check power TO the relay and check the power and grounds from the computer.

Blessings,
Austin Davis