I seem to recall a ground strap at the tank sending unit, make sure that is hooked up properly. The gasket keeps the sending unit from grounding. Now, keep in mind I haven't played around with mine in 20 years ,this is what I remember and it may be foggy. I remember hooking that ground up and it worked just fine. another thing I remember is my brass float had a hole in it and I brazed it to get it "floating again" it always read "empty" LOL! That was fun waiting for the gas to flash off then lighting a torch to "braze" it on the bench vise...
