I just bought a 86 silverado and went to fill up one of the tanks, and put a little in the other for "in case". Anyway, I thought it read the amount right but when I flipped the switch to the other side, instead of reading near empty, it went way past the full mark to right. Reads at about 3 o'clock..lol.

any ideas?

Matt

 

Check the wiring/grounds at the tank sending unit for good connection/lack of corrosion.