Please help me get started and restore my 1989 v12 XJS

XJ-S
1

Hi all, and thank you for the amazing information throughout the site & forum.

i have a 1989 xjs v12 that has not been running for 15 years. to cut a long story short it was fitted with a scorpion immobiliser (i believe at factory) which someone attempted to steal and remove in 2004 and its sat in garage since.
The car is a 1989 he v12 5.3 with Marelli ignition system
i rescued it from the owners garage and have pulled the immobiliser completely out throughout.
we tried starting and got spark for a second or so and than nothing, power is coming to both coils positive but no spark is coming out of either coil.

Has anyone got any experience with this on where to start? ive been mentioned to to look at cam sensors, temp sensor etc, was hoping someone could lead through the correct diag method.

Thanks for reading and regards.
Joe

2

A car sitting that long will have issues with fuel too. I’ll bet the tank has rust in it. I just bought a car that has only been sitting 5+ years, and I’m having to redo the ignition system and fuel system, including the tank. Sitting is not nice for engines. All rubber parts having to do with fuel should be replaced.

3

Joe,
I purchased a running 1990 XJ-S convertible (5.3L V12) for my wife in 2005 with 62K miles on it and it now has almost 130K miles on it. I have done most of the work on it over the past 13 years. Except for when I was work on it this car has never sat for any extended period as far as I know. So I haven’t faced what youare facing.

As far as where to start, I recommend that you first get a good library of the technical documents that you need for your car. In the long run this will save you a lot of time, minimize frustration, and save you money on parts.

Here are the documents that I find very helpful for my wife’s car:

-Owner’s Handbook

-XJ-S Repair Operations Manual

-XJ-S Parts Catalogue RTC9900CA

-S57 Electrical Guide

-Kirby Palm’s “Experience in a Book”

Fortunately for me the Owner’s Handbook came with the car. I purchased the ROM, Parts Catalogue and S57 on eBay. You can download Kirby Palm’s book for free from Jag-Lovers. I much prefer the hard copy versions of these documents. I believe that they might also be available in digital format but I don’t have experience with that.

At this point on a car that has sat for so long you could have any number of issues. If I were you I would drain the fuel tank and surge tank to inspect for rust and debris and change out the fuel filter. I would also drain and replace all engine bay fluids, belts and hoses. I would remove and replace the spark plugs and wires and perform a compression check to make sure that you don’t have a dropped valve seat.

Your engine will run if it has compression, fuel, and spark in the correct amount and at the correct time.

Although I have not had experienced the exact problem that you have, I have had failures of coils, crankshaft position sensors, fuel injectors, various sensors, and wiring.

BTW, read up on the “Marelli meltdown” failures of this digital ignition system in both Kirby’s book and in the online archives. It is certainly something for you to be aware of.

Good luck.

Paul

4

I am doing exactly what Paul suggested to my 1988 that has been sitting a while. You HAVE to suspect old worn ignition components and definitely a bad fuel system. Water in the fuel will rust any metal, and areas with no fuel will allow rubber to dry out. Plus, gasoline goes bad after I think 6 months? Or is it 1 year?

Instead of trying to determine what part is wrong, I am going to replace almost everything.(all fuel lines, tank and pump, pressure regulators, injector orings…) and most of ignition (coil, wires, plugs, GM Module in the ignition multiplier, rotor (my cap was fine)…)

At that point, I can determine what else needs looking at. But gotta make sure a good spark and good fuel w/ pressure is working first.

Def read through Kirby’s book. Where I see a part commonly fails and it’s not too expensive, I am going to replace it for preventative measures. 30 years old, it won’t last long anyways.

5

That is a long, long time for a car to sit and do nothing.
I guess you paid very little for it.
Even if you have all the tools and gear to fix everything yourself it could cost a small fortune, or even a large fortune, to get it all up and running again.
XJ-S spare parts prices vary from quite reasonable to pretty steep. You can at times make do with aftermarket or 2nd hand items.

Meanwhile you might be able to buy a running XJ-S at a reasonable price and spend less, and have the advantage of driving from the day you pay over the money.
if you have storage space you can use that car you just bought for spare parts or get it up and going at your leisure.

If the bodywork and interior are in good shape it is worth trying your luck to get it going. At worst you can always buy a 2nd hand engine from a car that may only be parted out because it is full of rust or there is collision damage.

If the bodywork and interior are still good then persevere and report progress.

6

Hi all and thank you for taking the time to respond, i am interested in getting this car restored &running on original engine as it has the makings to be a real classic, its got low miles, low owners, and amazing original bodywork as it has been in the dry most of its life.

my understanding from hours of research is that there are 3 sensors that can stop it sparking, the coolant sensor, crankshaft and camshaft. can anyone guide me on finding these and how to diagnose them? is there a computer system for diagnostics that these can be scanned on? i have noticed a round connector block about inc and a half wide in the bonnet on passenger side of bay was hoping there was something that could plugin!

7

No computer diagnosis for the XJS. Here are a few tips:

Kirby’s book has considerable info about the Marelli ignition system (unfortunately, no illustrations). I have no experience with Marelli (or the CPS) so I can’t help with that, but I did find this video:

and this Google hit:
https://www.jaguarforums.com/forum/xjs-x27-32/marelli-ignition-modules-127494/

An initial check would be to squirt starting fluid into the air intake while trying to start the engine, to see if it tries to start (catches, and then quits when you stop spraying the fluid); if it does, then the computer may be shutting off the fuel supply because it thinks the engine is overheated… focus on the CTS (coolant temperature sensor) and the wiring to it. The cooling temperature switch is on the top front of the driver side head; here are links to info on that:
Sean's Jaguar Tech Pages - A Coolant Temperature Sensor Emergency Switch
…check the wiring to the CTS first for broken wires or frayed insulation allowing a short.

https://www.jaguarfuelinjectorservice.com/Testing%20Testing%20the%20Jaguar%20Coolant%20Temperature%20Sensor.htm

The CTS is not expensive, so it may be worth changing it out.

Another common no-start issue is the ignition amplifier (but I’m guessing a Marelli car doesn’t have one) or the wiring thereto (short box about 4" square bolted down atop the left head). Easiest way to check that is to substitute a good unit for a test. If you can’t borrow one, then check the attached writeup for info on how to test the GM ignition amplifier module inside the box.
Repairing the XJS ignition amplifier.pdf (516.2 KB)

8

WayneC, Joe,
The Marelli cars do not have the Lucas Ignition Amplifier (DAC4103) but they do have two Ignition Modules (DAC4607) located on the upper crossmember above the radiator.

The area on top of the left intake manifold where the Lucase ignition amplifier is located on the Lucas cars is empty on the Marelli cars.

Paul

9

Thanks all, would love to report progress however been a busy week, i have however been reading up on the material suggested above…wish i had another running marelli car to help diagnose… will keep posted.

10

should have this sticker on the window if its jaguar dealer fitted.

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