How do you fix the gas gauge in a 1984 Chevrolet?

I have had a couple Monte Carlo's and they has fuel level issues as well (usually the sending unit goes bad). The only guarantee way to fix it usually consists of draining the tank, unbolting the tank straps, and carefully dropping the tank. A few jack stands, a jack and help from a friend will make it much easier. Get a flat head screw driver before you do all this to tap the lock ring on the top of the tank in order to release the sendiing unit. Then diconnect it and pop it out. They usually cost anywhere 30-60$ depending on where you get it.