Help

[Speedy_1234]

i have a 2005 trailblazer 4500 the gas needle only markes E does anyone know what it might be. Sometimes it moves to a 1/4 then it comes back down even when i fill a full tank

[maxwedge]

More than likely the tank unit is bad, a scan with a full function bi directional scanner can check this.

[jdmccright]

It may also be a defective stepper motor in the instrument cluster (the same model was used for all the gauge needles). Many GM vehicles in the 2002-2005 span have had problems with false gauge readings, especially the TrailBlazer/Envoy models. I've had my IP replaced once and repaired again. Apparently the original motor design was faulty, eventually causing to go haywire...RPMs at 7,000 at a standstill, voltage at 19V, fuel gauge at 3/4 after 300 miles, etc.

From your symptoms (steady reading, moves slightly but consistently with tank fill) I'd be inclined to agree with maxwedge, but there is another viable possibility. Hope this helps!