I just bought a 1988 F150, 5.0 EFI/C6 today, good shape, 2wd, 163,000KM. I am new to this site but have my own website for Mercury's and Meteor's. The gas gauge is wacko and bounces all over the place, when I put gas it went hard to empty. Any common problem area's to look at first that could save me time and money? I am a truck and transport mechanic so I will find the problem regardless, just looking to save time as other parts of the old beast need work too. See my sig below to view the rest of my ford fleet.

 

My '92 F150 has problems with both gas guages. The front guage sort of works but the back stays pegged on E. This seems to be a common problem from what I have read on this site. From what I have read the sending units in the tanks seem to be the problem. Personally I live with the problem by keeping up with my mileage. The fix is too expensive and not worth the return on the buck. If my pumps ever go out I will probably see about fixing the guages at that time.

 

Check the cleanliness of the connectors on the instrument cluster's film circuit.