2007 Lacrosse with 50k. My fuel range changes when I shut the car off and turn it back on. It also will go up while I am driving. When the range increases, the fuel gauge will also go up. Any ideas, it is a strange one?

This is probably from the fuel sloshing around in the tank.

Fill it all the way full and drive it the same way. Do you still see this behavior?

I should have mentioned, it does happen when the tank is full .I can fill it up and my range can be 300 miles. If I shut it off shortly after that and then start it up again, it will drop to 275 (those numbers are just an example).

Do you live in the hills? Any time your vehicle is going up or down hills it will change.

I live 50 miles NW of Chicago, flat as a pancake. It changes mostly when I shut the car off, and turn it back on!

It could be that the float arm is binding or something, or maybe the contacts are corroding or something. There'* also a lot of salt up that way, it could be something happening with wiring corroding or something. If it were mine, I'd drop the tank, pull the float, and test it both with a meter and by watching the gauge move on the dash while moving the float by hand.