my 04 impala 3.8 litre has a problem with the fuel guage , it works intermitantly , somtimes it pegs at full and somtimes it just doesn't read properly . anyone had this problem ? any help would be appreciated , thanks,,,, brian

 

as a quick 'fix'
techron - the newer version now has additives to help clean sulfur deposits from the tank- Especially the sending unit- this causes eratic behaviour...
worth a try...

 

i have a 04 impala as well...
something is wrong with the gauge sometimes

are those tank additives actually worth using?
techron the best brand?

 

in both of your cases, its either sulfir buildup or just a sender gone bad.
The bottle will run about $10.
Techron is one of the best out there. Its great they added the sulfir cleaner for fuel sending units to the mixture.
Techron is rebottled by GM and sold at dealerships under the GM name. same stuff, just different bottle.
Running techron may help with the gauge- if not- then at least it helped clean you injectors and stuff.