My 2005 Chevy Trailblazer Gas Gauge is stuck on Empty?

probably is the sending unit. years ago when the floats were made out of brass they would leak and fill up with gas and of course sink to the bottom of the tank and read empty all the time. the float would bonce up and down and cause the gage to move from time to time. could be your problem but probably cant just buy a float and will have to replace the whole unit. might be a bad connection also but will probably have to drop the tank anyway.