Fuel Gauge Trouble Shooting Help Needed!!

Does your temperature gage in the dash read wrong also? If so, both fuel and temp gages rely on the 5 V regulator in the dash, which commonly goes bad. In 1973, it is a rectangular shiny metal can that plugs into the dash circuit board (rear). But if you have rally gages (tachometer), I think it was still buried within the fuel gage in 1973. Either way, best to replace w/ an electronic Vreg ($30 ebay, search "voltage limiter").

Otherwise, you need to tap into the "body harness" behind the driver's kick panel and measure the sender signal (resistance) there and use simulator resistors (Radio Shack) to test the gage. Need a lot of alligator jumper wires.