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Tim West
Tim West, ASE Certified Technician
Category: Ford
Satisfied Customers: 4638
Experience:  ASE Certified Service manager of Firestone
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1992 Ford F150: fuel tanks..fuel pump..I have removed fuel filter

Customer Question

1992 Ford F150 with dual fuel tanks. Neither fuel pump will pressurize when ignition is turned on. I have removed fuel filter, so that is not the problem. I have swapped the horn & fuel pump relays, so I do not think the relay is the relay is the problem. Fuel gauges work when I swap tanks.
Submitted: 6 years ago.
Category: Ford
Expert:  Tim West replied 6 years ago.
Access the Light Blue/Orange (LB/O) wire at the self-test connector and ground it through a jumper wire with the ignition switch in the run position. This should result in activation of the fuel pump relay causing the selected fuel tank to run.
If the fuel pump relay activates but the fuel pump does not run, leave the key on and the LB/O wire grounded, then check for power at the inertia switch. Power comes into the inertia switch on a Dark Green/Yellow (DG/Y) wire from the fuel pump relay and leaves on a Red/Yellow (R/Y) wire to feed the fuel tank selector switch.
If there is no power to the inertia switch, remove the fuel pump relay and jumper relay holder terminal 30 to 87. This should send power directly to the inertia switch without grounding the LB/O wire or even having the ignition switch in the run position.
If the fuel pump relay is heard to activate when the LB/O wire was grounded but there was no power to the inertia switch until the two terminals of the fuel pump relay were jumpered, either the relay is defective, or there is a connection of the relay into the holder.
If power is present to and through the inertia switch but no power is reaching the fuel pump, remove the fuel tank selector switch and verify power is present to it on the R/Y wire from the inertia switch, then check for output power on the Brown/White (BR/W) wire when the rear tank is selected and check for output power on the Red (R) wire when the front tank is selected. Replace the switch or service the open circuit(s) as needed.
Customer: replied 6 years ago.
I will be thrilled to pay if this resolves the problem. I have not been able to locate the inertia switch or the self-test connector. I have the Ford service manual, but it is not much help.
Expert:  Tim West replied 6 years ago.
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graphic

The inertia fuel shutoff switch is on the right cowl panel, just forward of the door, and below the instrument panel.

 

Also SEE VIP TEST connector. drivers side

Customer: replied 6 years ago.
Both fuel pumps work when I ground the Light Blue/Orange (LB/O) wire at the self-test connector and turn on the ignition switch. Neither fuel pump works if LB/O wire is not grounded. What next ??
Expert:  Tim West replied 6 years ago.
If the fuel pump runs when the LB/O wire is grounded and the engine will start and run, check the LB/O wire for an open back to PCM pin 22 before replacing the PCM. graphic
Tim West and 13 other Ford Specialists are ready to help you
Customer: replied 6 years ago.
Engine will not start, but timing light shows plugs are firing.
Expert:  Tim West replied 6 years ago.
Well my friend this one has me stumped, I will need to ask for help on this problem.
Customer: replied 6 years ago.
You have been a great help - even if the truck still will not start - thanks
Expert:  Tim West replied 6 years ago.
Well thanks for the accept I feel bad I wasn't able to solve the problem.
Thanks again,