Intermittent Fuel Pump: No Pressure or Priming

[Feshdogg]

I have a GT500 fuel pump setup I have been running for almost 3 years now with an Edelbrock blower. I probably have over 50,000 miles on the setup so far, so it has been working for a while.

I went to start my car today and it could not start. I recently installed a new Optima yellow top, the starter was cranking the motor, I just wasn't getting any fuel. I was able to check my fuel rail pressure and fuel level through the OBDII port, and both read 'zero'.

I tried turning off the ignition several times to prime the pump and I could not hear it at all. I then tried starting the car again and still no luck.

After calling a tow truck (I was parked next to a parking meter ) I tried starting it one more time before he put me on the flatbed. Pump primed, car started, away I went.

I replaced the GT500 pump assembly and nothing has changed. Any thoughts?

Thanks!

Steve

 

[TexasBlownV8]

The pumps were likely not getting power. I don't know how you have the power feed and relay(s) wired in, but those should have been your first suspicions. How is the power feed connected, to the battery or to the bolt into the BEC?

I installed 'power-on' LEDs for being able to know when I have power to such circuits, so if there was an incident like this, I'd know if the pump circuits are getting power.
Also, the relay for power control could be loose, getting corroded connections, or just be getting bad.

 

[JeremyH]

I wold start by checking/replacing the relay in the trunk on the gt500 fuel system harness.

 

[Feshdogg]

Hi Guys,

To be perfectly clear, I have the Saleen version of the Dual Pump Kit. The only difference, the way I understand, is the harness. It is very similar but slightly different. Both kits include the Ford dual pump assembly and second FPDM.

I have a suspicion that something is up with the Fuel Shutoff Inertia Switch. But I will check out the relay in the trunk.

This has been a problem for a couple months now, and I never know when the car will start!

 

[JeremyH]

Replace the relay first. Then suspect the inertia switch if your getting intermitent voltage to the hat at key on.

 

[Feshdogg]

Replaced the relay in the trunk next to the FPDM's. Didn't fix it, no power. Took the relay out and jumped the connector with a paperclip, pumps primed.

Any ideas?

 

[michael.konor]

Trace back the wire(s) that power up the relay in the trunk all the way back to the relay in the engine compartment fuse box if necessary. Also verify the ground.


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[JeremyH]

Then the relay is not functioning properly even though the relay itself is good. So verify power in to the relay from the inertia wire at key on and verify the ground out from the relay to chasis is good.

 

[BruceH]

The fuel pump relay that supplies power through the inertia switch (powers the GT500 pumps relay in the trunk) is position 21 in the EBC. Like Jeremy has already mentioned relays go bad over time and maybe this one is becoming sticky.

 

[Feshdogg]

So like I said, I have the Saleen version of this kit. I decided to spend the weekend tearing the entire harness out, check all the connections, and see if I could spot anything. Well as I started looking at it, I decided to just replace it with a FRPP harness.

I have no idea why, but the Saleen harness has everything the FRPP harness has, PLUS a replaced connection into the inertia switch, a replaced connection with the stock FPDM harness, a replaced connection with the fuse block, not to mention the kit came used (from an unnamed site vendor) and it was all hacked up with butt connectors and half-ass solder jobs. I'm just going to throw this in the trash because I remember having problems with wiring it up 3 years ago. Not worth it.

I don't want to jinx it, but I think that by replacing the Saleen harness and completely re-doing all modified stock connections, the FRPP harness might fix my issues. If not, I bought a new inertia switch to try.

If you don't hear back, assume it's all good! Car has started the last 10 times since I replaced everything.

Thanks for the help!

Steve

 

[Feshdogg]

The fuel pump relay that supplies power through the inertia switch (powers the GT500 pumps relay in the trunk) is position 21 in the EBC. Like Jeremy has already mentioned relays go bad over time and maybe this one is becoming sticky.

First thing I tried was swapping this relay with another one in the fuse block. Then inertia switch button, then trunk relay.

Thanks!