Cliff Notes: The Nissan Z32 300ZX ECU triggers the fuel pump relay with a switched ground, the GM ECUs use a switched 12V trigger.
So how do I make the GM ECU trigger the factory Nissan 300ZX fuel pump wiring then? Easy... buy the LOJ Conversions LS Swap Wiring Harness, problem solved.
Ok, for a more serious answer for you DIY guys. You have a few options:
1. Run completely dedicated fuel pump wiring with a new relay, fuse, and maybe some upgraded wiring to the pump for high HP applications. Accomplishing this is simple, just use the GM signal to trigger a new relay. Wire the relay as shown below.
2. Use a relay to convert the 12V output of the GM ECU to a Ground signal. Wire the relay as indicated below to accomplish this.
3. Rewire the factory fuel pump relay to accept a 12V trigger signal. This will require cutting factory wiring to accomplish. The factory relay is located here:
Once you locate the relay, take a look at the diagram below. (Click for full size image, will open a new window)
So you can see here that the Fuel Pump Relay has four wires going to it. Two White/Black wires, one Orange wire, and one Black/Pink wire. You will need to cut the White/Black wire opposite of the Black/Pink wire. Tape off the wire that is left going into the car's harness. Connect the other side that is going to the relay to chassis ground. Now when the trigger wire receives a 12V signal, it will trigger the relay.