I have worked on this issue for a while. I changed the lamps to LEDs, cleaned all of the connection points even the small copper contacts on the insulating boards to the instruments (very poor way to make connections) to the instruments cluster earlier all of the gauges move freely. The fuel gage originally showed empty. After I cleaned the cluster I have a reading of the on the gauge that says tank almost 1/2 full. I can drive a long way before the gauge stars to move down then eventually the low level light comes on. I tested the existing fuel sending unit and it was showing the correct ohms of resistance. I decided to install a new sending unit anyway. The new sending unit is putting out the same ohms. I checked the reading at the connection point at CP7 still had the same reading. I have a voltage reading of 11.9 volts to the instruments without the engine running. Is that enough voltage to get a correct reading? I really do not want to take the instruments cluster out again. Every time I remove the cluster a piece of the plastic housing breaks off and have to glue and duct tape the pieces back on because the housing is very brittle. I have a small electronic device that can increase the voltage to the instruments cluster I may try that. Any other ideas before I have to take the cluster out? If I have to remove the cluster can I move the arm on the gadge to the correct level or is there a different way to adjust the gage?

 

To get the gauge reading right, you (sadly) have to clean the contacts within the gauge itself in addition to everything else. In case you did not do this, here is a thread;
https://www.jaguarforums.com/forum/x...ng-fix-267848/

 

Greg,
I did everything on the list of item to perform cleaning and sanding all of the connections including the boards that slide down and make contact with the gages. Those copper contacts on the boards are the worst way to make connections to the gages. The only thing I did not perform was to add an additional ground to the cluster. The fuel gage originally showed no fuel in the tank until I performed all of the cleaning. After cleaning the gage shows a little less than 1/2 full. The low level warning light works. In one of the post recommend grounding the tank grounding terminal. I will try that first before I open the dashboard.

 

As i remember it, there is an earth tab on the sender unit that is connected to the loom. It could be that the earth at the other end of the loom is poor, so it cannot hurt.