I finally got tired of this whole gas gauge thing and ran some tests. I have 2 pathfinders one that is a 1990 SE wrecked the other a 1991 SE. I took the pump assembly out of both and tested them using the factory shop manual. The 1990 SE Gauge was way off on the resistance scale. Cleaned the carbon strip off with denatured alcohol and then tested it and it was within the resistance scale in the manual. On my 1991 It was withing the resistance scale from the start. I hooked it up out of the tank and did some tests with a buddy. adjusting the float up 1/4 of the way up put the gauge at just above the letter E. The tip of the pointer just going through the letter E. This is the same as if the float was all the way down. No changed in the gauge, even though with the meter it showed a change in resistance. When I moved the float to half way up the gauge moved to 1/4 mark on the gauge. when I moved the float 3/4 of the way up the gauge moved a little over between the half mark and full. and when the float was moved to the top the gauge move to the full mark Just a hair away from the F but not touching the F. I think I may try and replace the voltage regulator for the gauges and see if I get some better stability in the gauge that may shed some light on why my temp gauge never gets to half way up it sits mid way between the bottom and half. The shop manual shows it about 3/4 of the way up between cold and half at normal operating temp.
Mark
BTW I also tested my low fuel light and it does indeed work. The gauge was throwing me off since it would say empty when I would still have a 1/4 of a tank.