Sender should be at 90 ohms for a full tank and 0 ohms for empty.
If there was a short it would be reading empty, so that's not the problem.
Try this... Unplug the sender wire (tan) from the harness in the trunk and then turn
on the ignition key, gauge should read past full.
If it doesn't, you have eliminated the sender(it's probably OK), it's either the wiring or the gauge.