Well Timo, I kind of get lost on your posts. Just make sure it follow the basic list. The loose screw seems like it causes a spade/wire to become on and off. So clean and tighten all the spade connections involved. As far as the sender, I would forget the spade. Bypass it. Splice so that the sender wire goes directly to the gauge as I said in my first post. Unless you enjoy chasing this around and you want it to act up all the time. I don't care what the internet says. A direct wire is best. No reason to bounce off the fuse panel.
HB: I was being sort of generic. Making sure everyone realizes, as I've tried to explain many times, that grounding "starts" at the component but has a torturous path to the battery post. A path of just touching.... and rivets and screws and bolts and wires and braided straps and spades and solder joints and connectors. Thru rust and paint and corrosion. It's a hard task to achieve after years of aging. It's up to us all to examine it all. Change it to be more solid. Some of the ground ideas from the factory has maintenance in mind. Ease of factory assembly. Building sub assemblies and just plain no good and too many "junctions". I didn't know, and still don't know exactly how a 60 Chevy gauge is grounded. I do know how it is grounded on my 60 GMC and have seen how on TF and AD. I believe they are all basically the same thru 66. Keeping in mind the 66 had "gauge clusters" and "non gauge idiot light cluster", BUT both have a fuel gauge, albeit different looking? Anyway the back of the gauge is the same on all years I've seen. That is: there is a 1/4 diameter round slug that is NOT the ground. It is isolated from everything. The gauge does have a "ground plate". Has a hole for this slug and possibly some other holes and slits. The stud terminals and the slug (meter movement rivet) are isolated from this ground plate. The plate is forced against a metal surface by the terminal nuts. This metal surface is part of the cluster panel (the beginning of the ground path) and you will see by observation how it's ground path is achieved. Thru the cab. Eventually to the battery negative post. The dash structure and path is a little different on each truck era/model. If by testing, a person sees that they have a ground problem with the gas gauge reading, they must observe and inspect and improve the path of the gauge and the sender. In the last month or two I have written "a book" on this issue here on Stovebolt.
It's all on the internet in various places. Trying to put it all here in normal terms and reasoning. I need things spelled out for me and tend to write like that.
