Does anyone know exactly what the 4 wires do that comes out of the factory fuel pump? They are red/black, black/white, blue/black, black/red.

This is on a 91' FC NA RX7.

Need to know which one is power, ground, and what the other two are.

Thanks!

 

black/white is the fuel pump power wire, solid black is ground.

not sure where you found those color combos unless you're looking at the body harness side of the wiring.

the red and blue wires are for the low fuel sender and the fuel level sensor.

these wire colors are common between all 2nd and 3rd gen cars.

the only one to be concerned about is the black/white wire.

 

These are the 4 wires coming out of the fuel pump housing and into the 4 prong white plug. I'm building a race car and I'm wiring a circuit just for the fuel pump.

Do you know which of the red or blue is the fuel level? Would be nice to get those back to the ECU so the dash displays fuel level.

Thanks!

 

ECU does not handle fuel level at all. See the free , online wiring diagrams for what each wire does.

 

Of the two wires you are uncertain about ground one of them (just for diagnostic purposes then immediately remove ground) and turn the key to on. If the fuel gauge needle rises then you know that wire relates to the fuel sender. If the low fuel idiot light turns on then you know what the purpose of the wire is for.

 

That sounds like a good plan, but my car is completely gutted and has no rear wiring harness since all I needed was brake lights and fuel pump to work. I am manually wiring those items now thus this thread.

This is a going to be a race car and don't need the idiot lights. I did find the wiring diagrams and I'm still not exactly sure what the colors are. Maybe I just don't know yet how to read wiring diagrams OR my fuel pump was not the original one to the car.

My pump plug wires are: black/red black/white blue/red red/blue

The corresponding wires in the fuel pump plug in the S5 wiring diagram is: B, LG, W/R, W/G

If I just line up my colors and the wiring diagram, it tells me black/red = ground, black/white = power, blue/red = fuel warning, red/blue = fuel level.

Since we know the fuel pump plug plugged into factory units, I could probably assume that the wiring I just mentioned above should be fine.

Sound good?

 

white and green is your sender