Jaguar Repair: Jaguar fuel system, charcoal canister, jaguar xj6

Question
My 1982 Jaguar XJ6 leaks fuel. The right sending unit float is bad, removed and checked unit today, everything checked good but float full and dont float. When I purchased the car and opened the right tank with the car running it overflowed. It was showing empty (caused by sending unit). When I filled the left tank it started leaking and continued to do so. I pulled the cover from the tank and it seems to be coming from the overflow. Could the solenoid be the problem? I checked the Ohms across the two wires and got 22 Ohms. What is causing the leak. There's pressure when opening the cap on the right tank but none on the left tank. Fuel does seem to draw from either tank when selected.
I asked someone else and did not get an answer  

Answer
Hi Boyce,
It is normal to have pressure in the tanks when you open either cap which relieves the pressure in both tanks. The pressure regulator valve is in a line under the right front fender just short of the charcoal canister behind the head light. It is set at about 3 PSI.

The fuel tank switching system works like this, the fuel supply switching valve is in the trunk near the antenna motor behind the spare tire. It is defaulted to the left tank so when there is no power on it or if it looses power the left tank supplies fuel to the pump. It only supplies fuel from the right tank when it is activated. The return valves are in the lower part of each rear wheel well behind a small panel. The left valve is normally open or if it looses power the return fuel will return to the left tank. It only closes when powered.  The right valve is normally closed and only opens when powered to return fuel to the right tank. If any valve fails electrically the left tank operates normal but you can't use the right tank.
A simple test of each valve is to connect a 12v power and a ground to it and listen for it to "Click". If it don't "Click" then it is either stuck or bad and it is not serviceable.
It sounds like the fuel switching valve has lost it's power or ground or the valve has failed. That's my guess but you need to test the system as I outlined above.
By opening the caps while the engine is running you can use a flash light to look at the fuel returning to the tank and tell if the correct tank is receiving return fuel as per the dash switch.
Howard