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Jaguar Repair/82 xj6 filling right tank to overflow


we had a left valve failure and subsequently replaces all return valves ( three in total )  upon replacement we are still filling right tank , i have checked that the flow stops then u select right or left tanks and it does the power to all three also is out when left selected and are all live when right is selected.  i am at a loss the right  tank is still over flowing when it is selected.

any help appreciated

Hi James,

If the right tank is over flowing when the laft tank is selected you missed one or more of the steps. If you selected the LEFT tank and looked in the filler neck of BOTH tanks and seen the fuel returning to the LEFT tank and NOT the RIGHT tank then it is impossible to over flow the right tank.

If you have selected the RIGHT tank and the RIGHT tank is over flowing then you have a failed SWITCHING valve in the trunk and the fuel it not coming from the RIGHT tank but IS coming from the LEFT tank.  In this case you need to first have someone operate the dash switching button and feel the valve in the trunk to confirm that it makes a "Click" when the right tank is selected and another "Click" when the LEFT tank is selected. If it does this then you need to pinch off both large rubber fuel lines from the tanks and remove the valve and apply electric and graound to the valve and it should "Click" and then try to blow into the Left tank connection and it should be stopped up completely and then blow through the RIGHT tank connection and you should be able to blow air from the RIGHT tank connection into the fuel pump connection ONLY. Now remove the electric connection and blow into the RIGHT tank connection and it should be stopped up completely. Then blow into the left tank connection and air should go through and out the fuel pump connection only.

This checks the function of the switching valve.

Another simple test is to select the RIGHT tank and run the engine and look in the filler necks and you should see fuel returning to the Right tank ONLY. Then while it is running pinch off the large rubber fuel line from the left tank to the switching valve in the trunk. If the engine dies then the valve has failed or there is no power and ground to the switching valve.

It is impossible to over flow the right tank unless it is drawing fuel from the Left tank and returning it to the Right tank.

Let me know


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Howard M. Fitzcharles III


Jaguar from the XK 120 to XJ-6 ser. 3 1987


Dealership line mechanic on MG, Triumph, Jaguar for 15 years, Instructor in commercial mechanics school 2 yr. Product information manager for piston and valve manufacture, Instructor & hotline answer man for import car parts importer 15 yrs.

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