fuel gauge on 2006 Chevrolet Trailblazer

fuel gauge shows empty with a full tank and sometimes floats from half tank to full tank and back to empty.I only have 35,000mi.on this suv.

Asked by for the 2006 Chevrolet Trailblazer
Before doing anything I suggest getting a bottle of Chevron Techron Plus. This additive will clean the fuel level sensor in the fuel tank. Drive with a tank full of fuel and a bottle of this exact type of additive, see if it helps.