A simple search on sending unit finds Custom Jim's advice.
http://www.stevesnovasite.com/forums/showthread.php?t=198197
http://www.stevesnovasite.com/forums/showthread.php?t=198197
I'm not understanding this. The ring touches the sender and the sender touches the tank. They are all continuous, aren't they? So essentially, the top of sender, ring and tank are all grounded, no?I was having the same issue...the locking ring for the sending unit was touching the tank itself, so i backed the ring off enough for the tank and ring not to touch. I was able to have my wife sit in the car with the switch on and she told me to stop when the gauge started working....no issues since. Just something to look at if you have not, may work for you as well.