33Chevy

Working on a friends 87 vette, spark but no fuel pressure, pump not activating. Have it narrowed down the fuel pump relay.

On the relay - Orange Line (E) has constant 12v and GRN/wht Line (C) powers on for the 3 seconds.

The tank sending unit has (3) wires BLK, Pink and Brown w/wht stripe.

Trying to determine what color wire powers the pump to test the relay...right now don't have any power to the tank pump.

65Z01

Here's the setup on my '88
FP Relay:
Dk Grn/Wht = relay enable from ECM
Blk/Wht = Ground
Orn = +12Vdc, in always hot
Red = FP power out to FP Fuse

FP Fuse (10A):
Red = +12Vdc, in when FP called for
Tan/Wht = +12Vdc, out to FP

Fuel Tank Unit:
Tan/Wht = +12Vdc, power to FP
Gnd (looks like case)

Have you checked the FP Fuse? If so check for +12Vdc on the Red wire & Tan/Wht when FP called for.

33Chevy

Thanks

Fuse is good...so it looks like the 10a fuse is powered by the relay red wire which sends 12v to the pump via the tan/white?

If so, I should be able to jump the relay "orange" to the "red" temporarily to see if the pump gets 12v. Indicating a bad relay?

Ed

Cliff Harris

This is a massaged version of the picture in my '86 service manual. The FSM does not show the FP fuse, so I added it:



This should be the same setup for an '87.

65Z01

Sounds right.

33Chevy

Thanks guys for the great responses!

It was a bad fuel pump!!! Thanks Again!