BNR32 GTR Fuel Relay problem

[dtru606]

Good evening all, was driving around town and car stalled during the drive. Got the car parked and narrowed down the issue to the fuel pump not priming or turning on at all.

For starters: 1990 BNR32, Apexi ECU and Power FC, Deatschwerks fuel pump.

To sum up all the troubleshooting I've done:

1. Shot power for fuel pump relay and coupling to cap of tank, 12v of power is provided for a second, then relay shuts off providing no power. (while key is in on position)
2. Installed R33 GTR fuel pump and once again pump is not priming.
3. Fuses all intact.
4. Provided direct power to Deatschwerks fuel pump, pump did not turn on. (Gonna get a new pump)
5. Swapped batteries to a new one.

Any recommendations going forward to try and narrow down this electrical gremlin? Is there a fail safe where the relay will not provide constant power if a pump is not installed?

Thanks!

 

[GTSBoy]

Look at the wiring diagram out of the service manual. The pump is controlled by the ECU, so you need to understand where the wires come from to know when they should be powered/earthed.  Randomly jumping power into the relay circuit is not necessarily going to help, and may do the opposite.

[JGTC]

I had hot starting problems after installing a larger fuel pump and larger grounding relay. It ended up being the original fuel pump module not wanting to send the correct signal to the pump. Once the module was bypassed, car now starts when hot without issue.

Just another thing to consider.