The gas gauge hasn’t worked since I got the car. I have finally got around to trying to diagnose it. When the sending unit wire is attached to the gauge behind the dash, it always reads full. When it isn’t attached, it reads empty. I tested the resistance (Ohms) at the sending unit wire when the tank was not full and not empty. It read between 29 and 30. Then, I took it and filled it up. It took 8.2 gallons. The ohms then read 12. I think I know what the problem is. But, I want to get the...

1965 Mustang, fuel gauge issue.