Fuel Pump Relay Question (Page 1/2)
Boozeman SEP 11, 10:25 AM
Good morning!

I've got an '88 Formula with the 2.8 V6. Pretty much stock. A couple of days ago, my fuel pump relay quit working. Yesterday, I replaced it. After replacing, I tested it by putting my multimeter on the ground pin and the fuel pump pin at the ALDL plug, and then turning the key on and off. My question is this: does the ECM energize the fuel pump relay EVERY time you turn on the key, or will it only turn on the relay when it senses there is no (or not enough) fuel pressure? I ask the question because when I tested the new relay, the first two times I turned the key on, the relay energized and powered the pump. The next couple of times it did not. The next couple of times it did, and so on. I was pretty much turning the key off right after the relay de-energized, and then turning it back on again to test. Should the relay energize every time I turn on the key?
Mickey_Moose SEP 11, 04:42 PM
There seems to be a timed delay - if you turn the key on and then off when primed and then on again within the allotted time, it will not energize the fuel pump.

What this time frame is I have no ideal, but I discovered you have to wait a bit.
Boozeman SEP 12, 11:04 AM
Thank you for the reply and the information! That is what I'm experiencing... just wanted to be sure it was intentional and not a bad relay...
88Fingers OCT 10, 07:19 AM
Hello there, where is the fuel pump relay located on the '88 GT? Thank you
Vintage-Nut OCT 10, 08:31 AM
The Fuel Pump Relay is located on the rear firewall in the engine compartment on the left, behind the driver's seat.




------------------
Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

[This message has been edited by Vintage-Nut (edited 10-11-2024).]

olejoedad OCT 10, 10:04 AM
It should be noted that although the FSM illustration shows three relays, there are only two relays in that location on an 88 GT.

To be certain which relay is the for the fuel pump, it is the one with a pair of orange/black wires.

The A/C relay has no orange/black wires.
88Fingers OCT 11, 07:04 AM
Hello guys and gals. Turns out the fuel pump relay on "88 GTs is in the front compartment on the passenger side near the heater hoses!
olejoedad OCT 11, 07:30 AM

quote
Originally posted by 88Fingers:

Hello guys and gals. Turns out the fuel pump relay on "88 GTs is in the front compartment on the passenger side near the heater hoses!



No, it is not.

The relays in the front compartment are for the HVAC blower high speed and A/C enable.
88Fingers OCT 11, 07:49 AM
Hello again, i don't have A/C in either car and no relays are there in the engine compartment as per the diagram.
Vintage-Nut OCT 11, 08:30 AM

quote
88Fingers:
...no relays are there in the engine compartment as per the diagram.



The factory location for the fuel pump is as stated in the image and 'hidden' behind the air cleaner housing.

However, if your GT was modified; a previous owner perhaps relocated the relay as it can be easily moved......

The fuel pump relay has four wires:
Black
Green/White
Tan/White
Orange/Black