I have a 2000 Grand Prix gtp. Recently replaced the transmission and has been fine since other than the security light flashing. Car drove fine so I wasn't too concerned about it. Went to drive it the other day and the car would start right up, then die within a couple seconds. I assumed the pcm was shutting off fuel due to a fault with the security system. Went and got a used pcm from a junkyard and took the car to the local dealership to have it reprogrammed. After reprogramming it the security light is gone but the car will not start at all now. Cranks but will not fire. While it was at the dealership, the technician looked into the problem a little further and discovered that the fuel pump wasn't getting power at the relay. However, if he ran a jumper wire across the relay the car would start for a second then die. He checked fuel pressure with the jumper wire in place and only got 15 psi, so they told me the fuel pump is bad. I plan on replacing the pump, however that doesn't explain why the pump would not be getting power through the relay without a jumper wire. Any suggestions? Already tried replacing the relay.
