another gas guage question

Way past full is zero resistance or shorted to ground. This will kill the gauge.
First thing I would do is disconnect the rearward harness connector behind the left kick panel. If the gauge stops working completely the problem is from that cannecotr rearward. First place I would look for a short in that drk. blue wire inside the trunk.
If the gauge still goes to max after harness disconnected the problem is from that connector forward.
Pull the instrument panel and search from that printed circuit board connector and downward. The dk blue in question is at the 12 o'clock position.