Fuel gauge not working properly

Hello,

It sounds like you have a faulty fuel sending unit for the gauge.
The fuel sender consists of a variable resistor, it is controlled by float that is attached, which goes up and down with the fuel level. Over time with all the up and down motion the resistor will fault.
Resistance should be 160 ohms (full tank) to 15 ohms (empty tank).

The sending unit is located inside the tank.

https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump

Please let me know of any questions.

Thank you.