Sometimes when I start my car the gas gauge registers full when its only half full. After I drive for a few minutes the gauge will correct itself. If I check the computer on the navigation it resest the miles since refueling. I also notice the car is taking longer to start. Do you think the battery could be going bad? Maybe something else?

 

fuel pump is acting up

 

Best thing to do is check out the Fuel pump, and the fuel pump regulator. My Dad's Benz did this often, and the fuel pump was the culprit.

 

Ive got a similar problem but 80% of the time i fill up the gauge only goes to 3/4 the way full and says empty when i really have 1/4 of a tank left, the other 20% of fillups it either works fine or works fine then goes back to understating my fuel also sometimes it will fluxuate hourly between my actual gas level and the understated amount. I just live with it and know that if i dont go over 350 mi/tank i will be fine. Usually i fill up after 150 mi or so because i like to have a full tank so the gauge isnt an issue for me

 

I think you got a float problem. The float is inside of the fuel tank.

 

gloat problem? how do i fix it?