Ive had a heck of a time getting my fuel pump to seal, o-ring issues apparently. Anyway the fuel gauge quit working, there is a black wire that was barely soldered to the housing, it has come off. Is this the ground for the sending unit?

 

Just clean it real good and use a electric soldering iron you can remove the sender and then solder it just lube the oring so it will sit right when you install the hold down ring