Black Z28

iTrader: (2)

What wires on the firewall do i need to run a fuel pump relay on my carb'd '88 355? i know i need a ground, key on power, and the main fuel pump wire. wat colors are they? thanks for any help

camaronewbie

If you still have the Oil Pressure Sending Unit (OPSU) originally located above the oil filter, you'll see 3 wires running to the connector - the two larger ones run the fuel pump. You can splice into them, and run them to the relay. These wires - one originates at the fusible link junction by the battery, runs to the infamous fuse tucked in the fenderwell behind the battery, runs from there into the OPSU, and out of the OPSU to the fuel pump.

What I did was just remove that OPSU, stuck in a OPSU from a 1986 car only had a single wire to run the guage, then I ran the two fuel pump wires to a relay like you describe, so that my fuel pump will only run with the key on.

Hope that helps.

Black Z28

iTrader: (2)

my motors outta a 73/74 c10 pick up and the the sensor your talking about is a 2 wire but my oil pressure gauge never wrked so i dont know wat wire is meant for the OPSU for the gauge. the tieing in of the relay made sense tho thank you for that, but by any chance do you know the colors? i think one is tan for the main power for the pump and black from the relay is ground and then all i need is a wire from the relay to a key on source?

camaronewbie

Yeah - if you still have the original wires from the Camaro in there, you should find the ld fuel pump relay wires, which are

1) green w/white - the ign on wire for the relay
2) black - ground
3) grey or tan - 12v + constant
4) orange - 12v + power to the fuel pump

the green w/white gets 12v with key on, which energizes the relay, and sends the 12v+ from the grey or tan wire through the relay to the orange wire that runs to the fuel pump if that makes sense.

bluegrassz

iTrader: (3)

I ran the Green/White wire from the relay to a 12v (key on) wire that goes to the wiper motor. I havnt had any problems with it so far.

If anyone thinks this is not a good solution, post up to help this guy and other that read the post.

Black Z28

iTrader: (2)

Sweet that makes sense. jus when my buddy threw my painless harness into there, he capped off the wires are the firewall and left em there, im jus trying to figure out what wire is meant for the fuel pump for constant power which is the tan wire rite? and then the rest of the wires should be on the relay