Fuel pump relay location on a 1990 mercury grand marquis.

fuel pump relay or ecu problem in car

It should be in the fuse box

Since you have replaced some of the ignition parts, have you checked fuel pressure and the fuel pump relay ?
Do you know what you are loosing when the engine dies ?

When you say the fuel pump relay is good did you test for power to the relay circuit ?

There appear to be 2 fuses that can affect the fuel pump. #8 which provides power for the fuel pump, and #4 which provides power for the fuel pump relay. Both of these fuses are in the High Current fuse panel, which is located in the engine compartment near the battery.

The warning in the owners manual states: Always disconnect the battery before servicing high current fuses.Ford recommends that high current fuses be replaced by a qualified technician.

Voltage drop test the electrical circuit , do know how to do automotive electrical testing . Lose connection , resistance in the circuit , lose ground Mastering Voltage Drop Testing with Pete Meier and Jerry Truglia Testing Electric Fuel Pump Problems with Voltage Drop Test

I'd have to test when problem is ongoing. When you first turn on key, no crank, you should hear the pump run for a few seconds then stop. For initial prime, the computer doesn't need rpm signal. Engine cranking, the computer needs to see rpm signal or it won't ground the fuel pump relay. W/o rpm signal, no spark at the plugs and no fuel injector pulse. I know your talking about fuel, but, when problem is ongoing, check spark and fuel injector pulse, engine cranking.
Intermittent problems are a pain, have to test when problem is ongoing.

1996 Mercury Grand Marquis 4.6L SFI 8cyl


Fig. 1: The fuel pump is located in the fuel tank. On some models it can be viewed from the side as shown here



Fig. 2: Electric fuel pump removal

The Relay - Fuel Pump is located: Under hood, driver side, front side of wheelwell, mounted in relay block.


Hope this help to solve it (remember comment and rated this).

Replace the fuel pump relay located in the fuse/relay box in the engine bay.

you can try just resetting the fuel pump switch located in the car

the switch is originally in the car for in case of an accident, however, if changed, chances are you also have to reset it

in my 98 grand marquis, the switch is on the left side of the trunk