Depends on your gauge. I planned to use common ground but found my EFIS was sensitive and had to run the ground direct. That meant isolating the sender even from the tank. I did a brief write up with pictures
here. Note: I went with the cork gaskets for the sender plates and the rubber gaskets for the sender itself, rather than prosealing everything in permanently.
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Patrick Kelley - Flagstaff, AZ
RV-6A N156PK - Flying too much to paint
RV-10 14MX(reserved) - Fuselage on gear
http://www.mykitlog.com/flion/
EAA Technical Counselor #5357