Questions and Answers

Tanks A Lot Ford Q. Dear Mr. Ciulla: I own a 1992 Ford F-150 4X4 with dual fuel tanks. For past several months, the truck is taking fuel only from the rear tank and not using any fuel from the front at all, even though the selector switch is switched to Front tank.

I took the truck to Ford. They are saying that the Front fuel pump's check valve is bad and are asking a hefty chunk of money to fix it. so I took it to another mechanic and after checking it thoroughly he claims that the pump is not bad because when he switches to front tank, the pump runs and fuel comes out, however, the front tank remains full and the fuel comes out of the back tank. The switch is OK, relay is OK, Nobody can figure out what is the problem. Please help.

Thanks,
MSK

A. I would have to look at the selector switch for the problem. This has been the most frequent cause of this problem in the F-150's I've seen.

The way it works is voltage is supplied to the Fuel Tank Selector Switch whenever the Fuel Pump relay is energized (contacts closed). When the Fuel Tank Selector Switch is placed in the FRONT position, power is supplied to the Front Tank Fuel Pump. Fuel is then pumped from the front tank. The signal from the Front Tank Fuel Gauge Sender is carried to the Fuel Tank Selector Switch, and then to the Fuel Gauge in the Instrument Cluster.

When the Fuel Tank Selector Switch is in the REAR position, power is supplied to the Rear Tank Fuel Pump from the Fuel Tank Selector Switch. The Rear Tank Fuel Gauge Sender signal is transmitted to the Switch, and then to the Instrument Cluster.

When you check the switch, you have to be sure it's sending power to one fuel pump or the other, not both at the same time.

Additional Information provided courtesy of ALLDATA