I'm stumped on the hookup of my fuel pump wiring in my 68 Chevelle. I've got the complete racetronics setup and added the Square Spectra # fpw3 connector for final hookup.
I've got the Grey wire connected to a 12v feed, the Purple wire to my(Tan) fuel level wire and Black to ground. The Bl/Wh wire in the Spectra connector is mated to another Purple wire in the Hotwire connector and that's the wire I'm not sure what to connect to.

Also is it the Grey wire in the hotwire harness the feed that Triggers the Relay in the hotwire kit ??? and should that wire come from my IGN Key or from the ECM.

Engine is an 07 Ls2 and I'm using a complete PSI harness system









Thanks, Tony

 

I still don't know what this Black/White wire connects to. It is purple from the fuel level sender on the Racetronics Hotwire harness. The other purple wire I have connected to my Dakota Digital controller but I'm getting an EEE code which means it's looking for a ground. My confusion is both purple wires from the sender are hot with key on so I'm reluctant to use one as a ground.
Dakota Digital is working with me on the code but won't advise on the Racetronics product. My car is a 68 Chevelle and the fuel level wiring is independent of the PSI ecu with the one purple wire connected to the tan fuel gauge wire in the American Autowire factory style harness.

Thanks, Tony

 

OP, first I have no experience with the PSI harness you have, however I have personally built similar harnesses to direct feed power for fuel pumps and headlights. The MP150 connector should receive a trigger from the ECU so that the pump primes for a few seconds with the key on. Within the same connector you should have a hot from the gauge and a ground for the gauge as it reads from a change in resistance caused by the float arm on a potentiometer.

Now, I have no idea what pump assembly that is, however I can ascertain with a certain level of confidence that in the 4-pin GT280 connector on the hat that the heavy gauge red is hot to pump from the relay fed from the alternator, and the heavy gauge black wire is pump ground, the other two that go to the MP150 connector are going to be hot from level gauge, and ground to/from gauge, and the grey wire in the MP150 that disappears into the relay harness is your ECU fuel trigger.

I would assume that the 4th and final wire from the MP150 connector that disappears into the relay harness is the ground for the relay trigger that comes from the ECU fuel pump trigger.

TLDR: MP150 pins to relay harness are gauge power, gauge ground, ECU fuel pump trigger signal, and ECU fuel pump trigger ground.

GT280 pins are fuel pump hot (heavy gauge), fuel pump ground (heavy gauge), gauge hot to MP150, gauge signal (ground) to MP150.

 

Ok so Dakota Digital is asking me to run a ground directly from by fuel level sender to their control box, would that be the Black/white wire leaving the MP150 connector ? Even though it's reading hot with a test light.

 

Gray = factory fuel pump signal +
Violet = fuel level signal
Violet/green = fuel level signal reference ground
Black = ground

You will find this info and more in our customer support forum.

 

You have 4 wires to determine from the MP150 (I can't see all of the colors from the pictures) the 2 that go into the harness are triggering your pump relay via the ECU, one is power, the other is ground. The 2 that go from the MP150 to the GT280 are fuel gauge sender, and fuel level signal. The signal wire is the ground that goes back to the gauge (it reads via resistance through a potentiometer attached to the float arm in tank). Your ground/signal will read hot with a test light because you are completing the circuit through the bulb to the test lead through the ground clamp.

 

Ok thanks everyone once I found out the B/W wire through the MP150 Violet/green wire was the ground reference wire needed and ground at the fuel pump clamping ring, I got all the proper signals to DD fuel gauge.
Now I will say this though that Violet/Green in the Racetronics Hotwire harness has the faintest green line that you can imagine and if not prompt it is easy to miss.

Thanks again, Tony