760 L6-2383cc 2.4L DSL Turbo D24T (1983)
Disconnect connection at fuel tank and measure the resistance across the white- gray wire and ground.
Main Tank Full = 36 +/- 2 ohms
Main Tank Empty = 296 +/- 15 ohms
If these readings are not obtained, replace sensor.
TIPS
If gauge reading is false e.g.. shows reserve when tank is empty, test gauges accuracy with the,new sensor, since the sensor is so difficult to remove.
If the sensor is removed, check it against specifications chart for accuracy.
Also remember, to check tank for obstructions e.g.. fuel baffles touching sensor.