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Jaguar Repair/Proper testing procedure?

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Question
Good morning Mr. Fritz harked,

I was reading some of the recent questions and answers on the forum when I came across Judy's questions regarding fule change over switch. What is the proper way to test the CBC-4269 fuel tank selector valve?  Then what is your suggestion in locating the correct and if possible OEM switch.  I believe the switch is faulty and would like to replace it and test the circuit.

Thank you,

Cooper Collins

Answer
Hi Cooper,

The valve is easy to test as is the system that operates it.

First confirm that you have no fuel fumes in the trunk area. Then disconnect the wire from the valve and have someone in the car turn the fuel selection switch to the right tank. With a 12v test light confirm that the wire is powered. Then take the wire and touch the wire to the wire from the valve and listen for a "Click" from the valve and there will be a small spark as you make the contact. Make the connection several times so you can hear the "Click" each time.

If you have confirmed power but get no "Click" but do get a spark then most likely the valve has either failed or is stuck. Now connect your 12v test light to the powered wire and test the black ground wire on the valve to confirm a good ground.

I have at times when a valve sparked but had no "Click" I was able to remove the valve (first pinch off both large hoses from each tank) and bump it down alternating hitting it on a block of wood on each end and thus getting it to release when one was just stuck due to trash. Then I blew through each direction with air pressure. I was able to save about a forth of failed valves that way.

I have only purchased that valve from the Jaguar dealerships. I order most of my parts from Engel Imports on line. They have always given me good service.

Howard

Jaguar Repair

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Howard M. Fitzcharles III

Expertise

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

Experience

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.

Organizations
Associate member SAE EAA member

Publications
Import Car magazine

Education/Credentials
ASE Master Auto with L-1 certification up to 2000

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