So, my 68's fuel gauge was working fine last weekend when I parked it. Started it yesterday and saw the fuel gauge go up to just past full. I put in gas before I drove it around the last time and went thru about a half tank. I might be getting old but didn't remember putting in more before I parked it. So I filled up the tank and it took 6.5 gallons and fuel gauge went higher about another 1/4 inch beyond full. As I drove 25 miles it went down 1/8 inch closer to full. I did the TAN wire ground test today actually did it twice, because the needle went up higher to about 3/4" past full. I measured the voltage at the TAN wire connector 7.7 v. What voltage should it be ? 12 ? In the winter Ill pull the gauge and test it, and the Tan wire resistance.
The fuel sender is 0-90 ohm unplug the connector to the sending unit in the trunk and check the resistance. If its showing more than 90 ohms that's where the problem lies But typically if you ground the wire the fuel gauge it would go to full if you don't ground the wire and turn the key on it should go to empty
