Gas Gauge

The metal clips snapped onto the fuel lines is the ground strap. Now that we know all 3 stock gauges are dead we know the limiter in the fuel gauge is dead.
The voltage limiter that is normally found pluged into the back of most panels in inside the fuel gauge on rallye panels.
I'm guessing what you thought was the voltage regulator is actually the noise supression capasiter. Go here and read ... www.DeMonIVR.com