my gas gauge is goofy too
the bobber is on the fuel pump
i replaced the bobber mechanism and checked to make sure the gauge was able to move up and down.
my car will throw the light up at 1/2 a tank, then it'll turn off.
then once the gauge goes to about 1/8th, it'll come back on, then the gauge goes back up to 1/4, then back down....idk
i just fill up at a certain mileage