1987 S-10 Blazer fuel guage malfunction?

My blazer has had alot of problems and this just adds to to the frustration. The gauge worked fine till one day I went and put gas in the car and it stayed on empty. I looked over all the fuses and it gets power to the gauge because when you push up on the gauge and let it set on full and turn the key to the on position it pulls it back down to empty. The car wont be drove till I fix all or most of its problems so.