Fuel gauge not working

Hi everyone, my fuel gauge is pretty much always at either half full or slightly above despite how much gas I have in my tank. I pretty much go by my mileage and the trip computer to see when I should fill up next, not a huge deal but it gets annoying. Does anyone have some suggestions on how to fix this? Thanks!

I just acquired my grandpas 01 LS MC, and i was going through his receipts for the car.  He at one point also had the fuel guage not work, the shop changed out the fuel level sensor, which is in the tank.  That fixed the problem.  If it's anything like my escalade, the sensor and fuel pump are all one unit..........

also make sure to check the ground for the guage at the tank.
if you get any corrosion in there it will break connection.
but honeslty the bad news is i think it might be the sender mos tof the time if you somthing liek this at half tank readdings it is the sender or the tank level sensor.

2000+ Monte's also seem to have an issue with the guages going bad.
I had to have my guage cluster replaced when the temp guage suddenly shot up WAY past maximum read out.
 
If it's not the problem the others mentioned with the sending unit, this may be your problem.
 

i'd put a fuel level sensor in it, the lil fingers on the sensor wear out.  if you feel youre competent enough, theyre pretty easy to change on our cars thanks to the access panel in the trunk, or if you have it done the labor isnt a big killer because of the access panel.

Most likely a fuel level sensor.If possible have your Monte Carlo's PCM scanned for diagnostic trouble codes. Diagnostic trouble code P0463 would be the fuel level sensor.