HiCustomer Thank you for asking your question on Just Answer.
95% of the time, when the gas gauge does not work properly, the sender (sensor) in the gas tank has gone bad and needs to be replaced. This would involved removing the tank and replacing the sensor. I don't remember if you have a separate sensor or if the entire assembly (including fuel pump) would have to be replaced. If you would like, I can look that up for you.
I hope this helps. Please let me know if you have more questions.
Take Care, Greg A.