the unit body is grounded. And i know has 1/2 tank of gas in it. Old sending unit read 33 ohms near half, new unit in tank reads 33 ohms, but gauge is just above e. spikes to full when i ground the wire. The gauge worked fine before i replaced it, guess i have to pull the new one out and run ut through the scale. I just thought 33 ohms would show alot more than just above e.