My fuel gauge on my 68 coupe started to read full all of the time. It used to work until a few weeks ago. I had purchased a new sending unit awhile back, with the tank empty, I dumped in a give amount of gas and verified the gauge was reading correctly for the amount of gas I dumped in. I had to drain the tank a couple of times, give the float lever a small tweak and check the indications again by dumping in a known amount of gas. After a few attempts, the gauge was reading pretty close to how many gallons were in the tank. But now, the gauge always shows full, or close to it. With the key off, the gauge will go to empty, turn the key on, gauge goes to full, or nearly full. Any advice on why it?s always reading full, nearly full all of the time?
