2000 Pontiac Grand Prix fuel pump post earlier

You need to post any replies or followups to your original post. With this new post, no one knows what the original question was or what tests have already been done, and the results. You can fill me in here too if you want to, but I'm not an expert on your car model. You're better off adding to your first post and hope Saturntech9 sees it.

OOPS! Saturntech9 is a good guy, but I was thinking about a previous post I just read for a Saturn. I'll still try to help if you if the problem is electrical in nature.

You're describing multiple symptoms that could be related but it's hard to know for sure. Years ago GM had an unusual fuel gauge circuit that used the sending unit in the tank to ground the signal wire and pull the gauge down to "empty". When the ground was lost, typically due to a corroded wire, the gauge would read "full" all the time.

On your car the fuel level sending unit is an input to the Engine Computer, then the computer shares that information with another computer module, the instrument cluster. The sending unit shares a ground circuit with the fuel tank pressure sensor so a bad ground should set a fault code related to that sensor. If you have access to a scanner, you can read the stored diagnostic fault codes to see if there is one related to that sensor.

You could also unplug the connector at the gas tank, verify the fuel gauge still reads "full", then jump the two sending unit wires together. If that makes the gauge read "empty", suspect the sending unit. The two wires to jump are the purple to the black / white.

For the fuel pump, lets start at the relay because that will let us split the circuit in half to see which half has the problem. You can pop the cover off your old one and install it that way, then squeeze the contact. A helper should hear the pump run when you do that. If it runs, all that wiring is okay and we have to look at what controls the relay. If the pump doesn't run, check for voltage feeding the relay first. That will be on terminal 30 or 87. If it's missing, there's a blown 15 amp fuse. I'm not aware of a resistor in that circuit.

You can also bypass the fuel pump relay with a jumper wire or stretched-out paper clip. Remove the relay, then connect terminals 30 and 87 in the socket. You should see a little spark there when you make the connection, and the pump should run.