I went to the ultimate extreme when grounding my sending unit. At NAPA they sell a two conductor wire encased in a gray outer covering. The red wire is my sender wire and the black is the ground wire which I hooked to the back of my gauge cluster. My gauge used to show having more gas than I actually had, causing me to run out of gas when the gauge showed a quarter tank. I wanted to eliminate this problem so I have the sending unit grounded to the actual gauge cluster.
