At my wits end, good ole fuel gauge troubles

FlamesAreWicked said

I did trim a little off the plug because I thought maybe the stud wasn’t going inside the plug enough..it’s bottoming out on the base of the stud, or so it appeared. It’s going on fully. It does have a flat at the top of the stud as the one with the arrow pointed to it.. it doesn’t have that little extra nub sticking out beyond the threads.. since the power probe has a pointy tip, it made me think that maybe the stud isn’t getting full contact.. just spitballing at this point

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I may have missed this (you may have done this already), but I ran into this when I messed around with the sending unit in Bazza's VG (an Oz-built Dart, if you will), and one thing that helped me was testing the circuit with a potentiometer (100 ohm, if memory serves). In other words, I put a pot in place of the sending unit, turned it until the gauge was on empty, recorded the value of the pot, then went to half tank, did the same thing, and then full. Turned out the sending unit was ok, and the problem was somewhere inside the wiring harness, under the dash. Been too long to remember exactly what it was though, sorry.