Fuel gauge had been dead for a while before I took the car apart for restoration and rebuild. In the process I installed a new gas tank and gauge. When I finally got it running the fuel and temp gauges were working. After a brief time both quit. They did seem to be a bit shakey but worked. I did some diagonistics and determined that the constant voltage regulator was dead. .12 volts coming out of it. Replaced it with an electronic voltage reducer. Wired it in and have 12 volts in and 6 volts out. Ran ground wires to the dash. Gauges still dead. Grounded both gauge wires at the sending units and both gauges went all the way over indicating that the gauges were good and the wire to the gauges and sending units were good. According to the shop manual this would indicate that both sending units are bad. I am finding that hard to beleive but it is possible. Checked fuel sending unit with ohm meter and there is definately resistance which indicates that the sending unit is not an open on the circuit. Also ran a jumper from both sending units to a good ground to make sure both were grounded and still nothing on the gauge. Next step is to pull the gas tank sending unit and bench check it and try another Temp sending unit if i can find one in my spare parts. Any suggestions as to what I may be missing? The only other thing I will try is to jumper a ground from the gauges to a known ground but I find it hard to think the guages would lose ground even though it sure seems like a ground problem to me. And yes there is a new ground strap from the engine to the firewall which shouldn't affect the gas gauge. I hate electrical gremlins!!