I had a similar problem on my 82 f100. the gauge registered empty, even
though gas was there. mechanic said it was float problem, said it was
so i dropped tank and pulled sending unit. the float was ok. I reinstalled
tank and it started to work again. now, it works intermittently. i haven't
worried too much about it since i have two tanks and don't drive the truck
very much. i assume that the contacts need cleaning, which i will do
sometime (when it gets cooler).
if you drop the tank, do not destroy the larger rubber hose that gas flows
into (when you're pumping gas). mine was difficult to remove so i was just
going to cut it off. i decided to get a new one before i destroyed the old
one. however, the inlet hose cannot be found, even from Ford. i was able
to reuse the old one. you might be able to find a flex hose that would
UPDATE: Well, it obviously isn't the gas causing my fuel gauge to stop
working, or any of the wiring for that matter. Went out this afternoon to
replace the inner/outer tie rod and when I took it for a short spin to see
if it was still in alignment, my gauge "magically" started working again.
Now it's reading where it should be, 3/4 and I haven't touched anything to
do with the gauge or sending unit since I replaced the old one last week.
I guess this is to be expected from a 23 year old truck, LOL. At least
everything else works OK on the truck.