I posted a while ago but still was unable to solve the problem. I replaced the sending unit in my 65 chevelle. When I filled up the tank it read about 1/4. I tested the new sending unit and it is working correctly. When I pull the brown wire from the sending unit the guage reads full. That means my guage is working right? I pulled the wires from the guage and didn't get an OHM reading from the brown wire. When I connected the black wire to the guage and not the brown, the guage dropped to empty. Does this mean there is a bad connection somewhere from the guage to the sending unit? Also, this might be a dumb question, but does tank size matter. The car was originally a six cylinder. Did they make a 15 galloon tank? Might be irrelevant.