[formulaross]

Well, you've got the dash gauge, the wiring in between, and the sending unit.

I suggest taking the dash gauges out carefully and check to make sure all the connections on the back side are snug. My dad had a fuel gauge in a Chevy van that didn't work and only needed a nut on the back of the gauge tightened up.

While you have the gauges out, disconnect the wiring harness from the fuel tank, get a good schematic and multimeter and verify the wiring between the gauge and the tank sending unit. Check for proper power and grounds, too.

If you haven't found any problem by this time, you may be in need of a new sending unit which resides inside the fuel tank.