Help with Temp, Gas, Oil Alt gauges FREE VIDEO INCLUDED!

Dang if I know. The amp gauge should work regardless. It dont need a ground at the panel. Even if the 2 wires were attached reversed polarity a good gauge would still work just backward. The 2 inline board connectors weren't keyed more than pin location/spacing. They can be attached wrong. If illumination bulbs work both sides of the panel, we know the orange wires are where they should be and we know the panel is chassis grounded. From that can we assume all of the wires are on the proper pins? The temp sender wire should be purple. The fuel sender wire should be dark blue BUT... Going back to my earlier comment, What should have been blue with white tracer from ignition switch to inst' regulator was found to be black in your connector. It has been butchered then taped up and we are assuming its good.beginning of this thread the fuel gauge was responding just very badly. Now it doesn't respond at all?
I can't fix it from here. If I was there I would have factory diagrams and check the right color wires are in the right ports and on the right pins. I would prove 12 volts into the regulator, 5volts to the 2 thermal gauges, and then start checking the sender side of those. I know I have power going through the amp gauge, otherwise NOTHING inside the car would have 12 volts. So I would save that one for last.