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Jaguar Repair/Fuel pressure for 1987 Jaguar XJSC


QUESTION: Hey Howard, Where do I check the fuel pressure, and how? The car will fire when you spray starting fluid in it, but won't keep running. I have checked what you told me about the pump,relays and etc.It semms to be OK. Thanks Roy


You will need a "T" fitting and fuel hose with your pressure gauge. Connect the "T" fitting to the fuel hose at the fuel rail or if it is easier just connect your fuel pressure gauge in place of the cold start valve on either bank.

You must not try to test fuel pressure directly on the fuel supply hose without a "T" because the two fuel pressure regulators must be in the system when testing.

After you make the proper connection of your fuel gauge, remove the small wires off of the ignition coil. Then go to the trunk and put a jumper from pin #85 on the fuel pump relay to a good ground. Now turn on the Ignition switch and you should see from 28 PSI to 30 PSI on your gauge.

Let me know,


---------- FOLLOW-UP ----------

QUESTION: I pulled the wire off a spark plug to test for fire , I don't have any fire. What next?

Hi Roy,

First look inside the distributor cap to see if you can ID the type of ignition system it has. I worked on the 12s for a few years and seen several changes made by Jaguar and Lucas and also there are aftermarket systems so you first need to ID the unit. If you can't ID it, take a photo of it and maybe I can ID it and if I can I will dig through my stuff to see if I can find a test procedure for it. Even if we can't ID it there are several things we can test around it thus narrowing the problem closer.


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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.

Associate member SAE EAA member

Import Car magazine

ASE Master Auto with L-1 certification up to 2000

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