fuel range indication freak out !

[squirrely_1]

hello, i usually don't post about my newer chevy but i am at a loss..My fuel range estimate just starts dropping as soon as i start my truck, then it climbs then it drops and sometimes the fuel needle with follow suit?..I have owned several chevy pickups, and back in the day when your fuel guage started not reading or freaking out then it meant a fuel pump change was in your future. Is this an indication on the newer Chevy trucks? I figure must be a sending unit thing, or is it something simpler? All replies are appreciated !