fuel tank sending

These are a simple series circuit

The voltage limiter is supplied by the "ignition run" line which powers the cluster and warning lights (oil light)

The output of the limiter goes to both fuel and temp gauges, so if the temp gauge seems OK, the limiter is at least functioning

From the sender terminal of the fuel gauge, the sender wire goes down to the left kick panel, to the connector at the rear harness under the sill plate and to the rear, to the tank.

So if grounding the seder wire does nothing, try grounding the correct wire in the kick panel at the connector, and if nothing, time to pull the cluster.