1987 5.8L Carb. Fuel guages don't work
 

I recently bought a 1987 F150 XLT Lariat extended cab with a carburated 5.8L V8.

Neither the front or rear fuel guages function correctly, so I never know exactly how much gas I have.

I am guessing that the floats in the gas tanks need to be replaced. Is this correct?

Has anyone had to do this on one of these?

Could be a failure of both gauges, or a problem with the switch controlling the operation between the tanks, or a wiring problem between the switch and the gauge.

Suggest to get ahold of a shop manual with electrical schematics in efforts to save unnecessary efforts and parts replacements.

check the fuses 1st

The guages work, they just do not give a correct reading. The switch for front/rear tank works also.

When I fill either tank up the needle goes WAY past "F" for full. Then as the fuel is burned out of the tank (around 1/4-1/2 full) the needle will bounce between 1/4 & 3/4 until it suddenly bottoms out at "E". Then you'd better gas up quick cause there's not much left in that tank.

^^Got the exact same problem with my tanks except the front one leaks like a sive....

That makes three of us. Mine don't leak, but the guages act about that way. Mine is a 1988 F-150. Has been that way since I got it. I don't consider it to be a big problem. I fill both tanks and reset the trip odometer, then refill with gas before I get too far into the second tank.