gas gauge

02 chevy impala LS 3.8L

For some odd reason my gauge never works right.

When I pump gas and I get to 3/4 of a tank it sticks and pumps 10gals of gas in before it gets to full.

question: what would you check first?

Could be a bad Fuel Level Sender.

I had a similar issue with my 05, I changed the fuel level sending unit and it did nothing. I have heard the instrument cluster maybe faulty and need replacing as they go out often.