2003 serria fuel gauge goes all over the place stays on empty the up and down also have engine light on code saying large evap leak new fuel pump and sending unit a year and a hlf ago
It's probably still the sending unit.(VERY common with GM vehicles) Where did you get the one you put in a year and a half ago? the EVAP code is probably the vent valve or charcoal canister but it could be the gas cap(it's almost never the cap though).
sending unit is a GM part
It could be a pinched wire shorting out the wire to the cluster? It could be the cluster itself. I've replace A LOT of them over the years. 1999-2006 where just bad clusters. Enough GM had a recall on them (but I think it has to be under 80 or 100,000 miles)
Looking for a Used Sierra 1500 in your area?
CarGurus has 66,147 nationwide Sierra 1500 listings starting at $1,995.
Search GMC Sierra 1500 Questions
GMC Sierra 1500 Experts