Fuel pump relay wiring.

[snoopjonnyjon]

I am using an aftermarket fuel tank and electric fuel pump, feeding a carb 302 in a 92 Ranger. This weekend was the first time I got any wiring back in the truck. I'm a bit confused what is the best way to wire the fuel pump relay.

I left the 3.0L computer intact, as well as the inertia switch. I extended the original wiring to work with my pump. When I turn the key on, the pump runs for a few seconds and then shuts off. Exactly as you would expect in a stock vehicle. However, after that initial burst, the fuel pump never comes on again. From my understanding, the fuel pump relay is triggered by the computer, which is triggered by injector pulsing. Since I do not have injectors pulsing, the fuel pump doesn't run.

What's the best solution here? Just wire the relay to trigger whenever the key is in the run position, or is there some other method that people use? I know I can make it so the fuel pump runs whenever the key is on, but it would be slick if I could retain of the functionality of the pump running when the engine is running. BTW, I am running an MSD 6AL box and Pro Billet dizzy.

 

[Earl43P]

I believe putting a PIP signal into the installed computer should do that for you. Existing PIP IN from the ICM is a GY/O wire into the PCM Pin 56 or 58, I can't tell which (bad copy). Splice your tach wire to there and see.

Injector pulse is not what "does" the fuel pump. Gotta be either PIP or CID, I'm betting PIP.

 

[snoopjonnyjon]

I believe you are correct that the PIP is what does it.

From my research it sounds like the PIP would be a 0-5V output, and the MSD tach output is 12V. Anyone know if that's going to kill my computer or not?

 

[snoopjonnyjon]

I've been trying to find a way to achieve this, but think I might just give up and wire the fuel pump relay to switched "run" power.

 

[snoopjonnyjon]

In case anyone ever searches this wondering what I did.... I just ran the blue/yellow wire from the relay to ground. The relay already had keyed power to it. The computer only controlled the grounding. The pump now runs whenever the key is on.