Ground wire on the fuel sending unit?

I recently have been trying to troubleshoot my fuel gauge not working in my 68 chrysler newport. Everything is new as far as the tank and fuel sending unit. I figured it is the ground wire but when I took the old tank out there was only the one wire which was the hot wire. No ground wire or anything not even a piece of a torn wire could anyone help me out with this.
Author: mrzods13