Use teflon paste, thread sealant, instead of the tape. Not because it blocks the ground, because it doesn't. But because the tape can end up in the oiling system. If you bought the complete gauge (instead of just the sender), the instructions specifically tell you not to use tape.
As an example, here's the instruction sheet for autometer gauges:
https://www.autometer.com/media/manual/2650-1079.pdf They specifically tell you to use the paste.