I have a 2004 Chevy Malibu with 67,000 miles and a V6 emgine. When I fill my tank, as soon as I start the car, the gauge drops to empty and the alarm sound goes off. It reads empty till I use up a couple gallons of gas then the gauge will go up. The guage know fluctuates and moves up and down so I really do not know how much gas I have. It can read a half a tank for 100 miles then all of a sudden it drops to below a 1/4 of a tank. No consistency. Where is the gauge that reads the gas level, inside the gas tank?