Gas Gauge

The other 2 gauges do not work.
There is no ground strap at the sender, (that's what those metal clips are on the lines!!).

The voltage regulator was attached to the gas gauge only, but is it linked to the other gauges by the electrical board?
I tried 2 different boards, one from another parts dash.

Since someone hacked up the harness I followed the wiring diagram and fixed some things, installed aftermarket temp, oil, and tach- but no gas gauge.

I will try to ground the sender wire and see if the gauge needle pegs full, but if it doesn't it is looking like the wiring is bad, (or more).

I am loosing my vision following the diagram, any idea how the wiring should be, including grounds, so I can at least install a gauge under the dash?

You guys are the best, thank you.