Okay this happened the other day as I was leaving campus. It was hot outside, i'm guess high 80's/low 90's. I get in my car and start it, the gas needle rapidly drops to Empty. So I'm thinking what the hell? I was at 3/4 when I parked that morning. So knowing that I have gas in the car, I drive off. About 3 minutes later I look at the gauge and nothing has changed. So I'm still wondering what's wrong with the car? I'm turning on the AC since it's hot, and as i'm about to adjust the temp. setting since it was cool that morning and i had the heat on i notice the gas needle starts move upward fairly quick. So I left the heater running, put it on max and put the front windows down. After a minute or two, my gas needle is back to 3/4. Was the heat in the engine bay causing my gauge from reading correctly? Or is it something else, it's once before but the needle never dropped that low. Any help someone can give is much appreciated and much needed. Thanks