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It's not the fuel pump, so what the heck is it? 2008 GP

mitchd123

New member
My son is struggling to get his car running. 2008 93k miles. I feel bad he lost one of his jobs, and he's struggling to make a car payment on a car that's not running.

He was driving along up a slight incline about 50 miles an hour and the car died while driving. The car would not restart. He rolled off into a parking lot, and we had to have the car towed.

1) He poured some fuel in the intake it starts and runs for a few seconds. Problem is fuel not spark.

2) I swapped the fuel pump relay....no change

3) There's no fuel pressure, so he decided to swap the fuel pump....no change

4) During the troubleshooting he broke the fuel pump relay socket in the underhood fuse box while he was checking for power. He ended up having to buy another UHEC box at the junkyard. So he swapped the underhood fusebox(UHEC) which came with fuses and relays.....no change....so it's not the UHEC box

5) I eventually pulled the cover off the fuel pump relay, and manually pressed the relay into position. The fuel pump started working. Tried another relay...no change. We checked the old fuel pump, and that also worked. So it's not the fuse, pump or UHEC.

6) Checked the PCM fuse/other fuses. The car runs if you put gas in the intake.

So now we're stuck? Apparently the computer (PCM?) is not telling the fuel pump to start. Before he runs out and dumps some more money on a new PCM / Computer, are there other components which could be causing the computer to disable the fuel pump....like security? safety?

What do you think is causing this ???? He's pretty depressed over the whole thing....this GP is his baby. He wants to wire the fuel pump to his radio circuit, and I told him hell no.


 


I've seen bad MAF sensors and bad MAP sensor cause no starts.

If it starts with the MAF unplugged, then thats likely the issue. I think you can try unlugging the MAP aswell and seeing if it will fire.
 
08 fuel pump.jpg
Here is a wiring schematic for the fuel pump. Check to see what you are missing at the relay. One terminal should be hot all the time, either the terminal next to that one, or across from that one should be a ground all the time. Whichever of those 2 terminals is not a ground will be the power from the PCM to energize the relay. The terminal caddy corner from the hot all the time will go to the fuel pump. If you connect a jumper wire from the hot wire to the fuel pump wire the fuel pump should run.

Let me know what you are missing and I can help from there.
 
Eventually my son gave up on chasing this and had the car towed to the dealer. I turned out to be some broken wires in the engine compartment. The dealer repaired the wires and it's been fine ever since. The signal was cut between the PCM and the UHEC / under engine fuse box.
 


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