Fuel gauge

There are 4 types of sender, one for a gauge, one for a warning lamp, and one each of China made crap.
I suppose it is possible to wrap so much teflon tape around the senders threads that it would be isolated from chassis gorund.
The sender is the only ground path though. The gauge itself is isolated from chassis ground in the instrument panel.
At first glance the gauge will look as if it is mounted to and contacting the metal housing. The housing is cut away behind the gauge can so the gauge contacts only the circuit board.