I am updating an old post, because first, I am the one who started it, and I wanted to provide an update. And second, thanks to those who provided clues. As noted, the fuel sender is on the top and driver's side of the tank. Road gunk was mentioned, as possibly hiding the wiring, but I am thinking it is also fuel seepage. In any case, while parked at Master Tech in Elkhart to have the windshield replaced, I purchased a can of GUNK engine degreaser and thoroughly washed the wiring at the sensor.
The gauge has worked ever since. A combination of road materials and seeped fuel, either shorted or grounded the circuit.
My apology to Master Tech, but the ground there was already stained.
Tic Wilson
2005 Beaver Monterey