Fuel Guage 2004 cavalier

i have never changed a fuel gauge so i cant help you there but you might want to check the float on you fuel pump

It may not be your fuel gauge. I have a similar issue with my Buick Terraza. It is the sending unit inside the gas tank. I was told by GM that the tank has to be drained, (safety of course), remove the tank, then then air out the tank to remove any flammable fumes, open the tank removing the bad sending unit, then put it all back together again. My issue is when I refuel the car, the gauge reads empty. The "check engine light" comes on and I get a "low fuel" read on my cluster information center on the dash. This can be cancelled of course, but it will continue to show low fuel and the engine warning light is on. Only around $800 to fix. I have several acquaintances with the same model and year Buick Terraza and they have the same issue. So first check with the dealer and see if the computer will tell them if it is the gauge or sending unit. After about 1/16 of a tank is used, the gauge will read correctly and all warning lights go away. When the gauge gets to 1/8 tank, the gauge will drop to empty extremely fast. I know I can go 325 to 340 miles on a fill up, so I set my trip meter to zero on fill up and use that as an indicator of when to refuel. On my long road trips, I can get 425 miles on a tank, but if I am in open country, don't push it over 350 miles to not be stranded.

Oh so true. The sending unit in the tank in more than likely the problem. You must replace the whole assembly( module, pump and housing). Not a difficult job, but time consuming, Be careful with the plastic fuel disconnects, will break if not then you get a whole new problem. On the outside that it is not the sending unit, you replace the whole instrument cluster. Very expensive fix, and not just something you go to the local salvage yard and get. GM's security will lock you out if it is not programed to the serial number and VIN number. You will not be goin' very far with that. Remove dash fascia and the 4 bolts that secure it in, single connecter in back. A shop with a MODIS or TECH2 can test the gauges without taking it out, verifying without crying.