My gas gauge reads empty with 5 gallons of gas. It is a new sending unit. All the wiring harnesses have been replaced in the car. I did an ohm sweep and the sending unit reads 10-70 ohms on the bench. I removed the new sending unit and it works outside of the tank. The gas gauge reads correctly in the different levels (empty, half, full) outside the tank. When I reinstall it in the tank, it reads empty and 63 ohms. I tried an additional ground to the sending unit while it was in the tank and there was no change. Thanks in advance for any suggestion! My friend's 66 Falcon has the same issue.