89 XJS, Stopped while driving

I hope someone has an idea about my situation.
I was driving the car then it just stopped (luckily I was not on a main road or freeway), I could not restart the engine, I tried turning it few times but it would not start, I had to push it into a parking space. Next morning I cranked it few times without luck in the end I tried one more time, it then started. It’s been working since then but no answer as to why this happened, my mechanic changed the temperature sensor on the left side, I think it has to do with ignition control (not sure). Lucas system
If anyone has an idea please let me know

Thank you.

Hello Hans - first thing - welcome to Jag-Lovers - great site with good knowledgeable folks - my suggestion is to check and see if you have a loose. or poor, connection at the front crank sensor as this could give the symptom you have described.

Lucas system, so no crank sensor

I would suspect GM ignition module. When was it last changed?

I was thinking that since he had “89xjs” by his name, that he would have the crank sensor, oops - didn’t pay attention to his statement of “Lucas” - yes, I agree that he would then need to check the ignition module for possible wire, or module, problem.

There’s also the stinkin’ little white coax wire from the ign amp back to the firewall and over the engine to the other side that’ll need checking.

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Welcome Hans,

Another possibility is a bad FPR.
Easy to check, remove the vacuum hose, if it has traces of gas the FPR is bad.
Also, can you hear the fuel pump working?

So many possibilities without knowing the history of the car and maintenance.

Some excellent suggestions thus far. I’d also add potentially plugged fuel filter and/or the strainer in the surge tank. I’ve also had a failing fuel pump that would make good pressure for a period of time, then heat up and quit. It cools off and car restarts no problem, lather, rinse, repeat.

Thank you, I will follow up on you suggestions.

I did not check the fuel pump yet. I think it’s old. The car has 75K miles on it I did nit see that changed in the records although they are sparse.

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I don’t Know what you mean by GM, but I know that most of the things on the car are original.

Thank you, I will check that.

Thank you, What does FPR mean?
The pump is working because the car is starting now. But I am worried it can stop any minute while driving.

Thank you, I will change those parts, I think they have been on the car for years.

Hello Hans - you are welcome - FPR means Fuel Pressure Regulator - used to maintain correct fuel pressure at the fuel rail for the injectors. In the black box, with the red label, usually mounted on top of the left hand intake manifold ( B bank ) towards the rear, there is the ignition module - this module was used by GM - General Motors, the name of the main conglomerate company consisting of the Chevrolet, Buick, Pontiac, and Cadillac companies in the USA. This GM module unit is a direct replacement for the original unit in your ignition amplifier and is usually available at most auto parts stores worldwide.

If your GM ignition module is OE, I’ll bet thats it. Search archives, its quite easy to replace. ONLY get GM Delco brand, about $40. Make sure to use plenty of electric heat paste. Many of us here keep a spare in the car, as it can go bad in ten years or less. It fits in ignition module box on top of B bank intake manifold. It controls ignition, without it, no spark.

General Motors. Delco, a subsidiary made the ignition module Jaguar used. Very heat sensitive,

Thank you very much, I heard about this, I will change it anyway. I am in California, I will easily find one.
It might be possible because this usually happens when the car is hot.

Giveaway is the heat. We were just talking about this a few weeks ago, the heat of the V12 can get that ignition box up to 180F-200F! Not good for electronics.

Many have found (me included) that the genuine GM Delco brand is the only one that seems to cope. But for how long?

I have added to my maintenance list to replace mine every 5 years regardless. $40 and 30 minutes of work is worth it.

Thank you,
Is there a part number for the GM Delco part.

Yes, GM AC Delco D1906. Should cost between $30-40. Anything over $40 is a rip off. Anything below $30 is probably not an AC Delco.

And I would buy some silicone heat sink compound. The little amount that comes with the module is suspect in my eyes. You want to make sure you get an ample amount on the module, without smothering it too thick.

If mine doesn’t say GM on it, and come in an AC Delco box, I send it back.


Great, Thank you very much.