I have a 1988 F150 Supercab 4x4 which I have acquired from my brother... it has a couple of problems... One which is the fuel gauges register full even if you have driven for several hours. Then all of a sudden it will slowly move and then go back to full. Another problem is that the wipers will only go on fast and the washer fluid doesn't work. For this I have changed the switch, which didn't help. Any answers to my problems?

 

Fuel intermittent relay bad. Fuel Tank sender bad in tank. Headlight switch on floor can cause issues too. Try stomping on it if your headlights stop working for no reason.

Frank

 

I highly recommend getting a Haynes, but read this caption first:



The fuel relay has nothing to do with the gauge. Check the wiring from the instrument cluster to the tank switch to the tanks. Polish the cluster connector terminals with brown paper or a pink eraser. Test the gauge side of the switch in each position (Y/W to Y/Bu & DB/Y).



If they're all good, the fault is in the tank sender. It can usually be repaired, but either the tank has to come down or the bed has to go up. I prefer to lift the bed.



If the sender is too bad to polish its contacts, replace it.



Check voltage on the Wh wire at the wiper motor with the key in RUN and the switch in LOW speed. Apply 12V across the washer pump terminals.