Hey guys, I recently got a 1987 Jaguar XJS with the intention of restoring it. The owner I got it from had it running 4 years ago and had all fluids changed before it got covered and left to sit for 4 years. When I got the car I wanted to see what was working and what wasn’t so I hooked it up with some jumper cables to my truck. The electronics (lights, windows, radio, etc.) worked perfectly fine. However, when I turned the key in the ignition all I could hear was a solenoid closing. The engine won’t crank at all. I’m not very familiar with the v12 setup so I’m not sure where to start troubleshooting. Any ideas on why it won’t crank? Thanks!

 

Hi XJS87

If you look under the Bonnet/Hood, to the Left and Right of the Closing Panel which goes over the Top of the Rad you will see a Bunch of Earth Wires secured by a Single Bolt at each end of this Panel

These Earth Wires need to be really Clean or else they could cause you a whole World of Problems either now or later on and also the Same in the Boot/Trunk where there are also some Earth Wires, that are attached to the Fender/Wing near the Battery

Though having said that its more likely that your No Crank Problem, has been caused by Disturbing 'The Fuseable Link' which you will find is Clamped to the Positive wire of the Battery (See Photo)

One of the 'Quirks' of the Fuseable Link, is that you can disturb it without even knowing that you have done anything wrong which 99% of the Time, can happen when Jump Leads are put on the Battery or the Battery is being disconnected or changed

Just 'Flexing' that Link between your hands, is sometimes all it takes to Fix it but even so you need to make sure that the spade Connectors in the 'Fuseable Link' are pushed right home, in order to lessen the Chances that it might happen again

Try that first and if that doesn't work, then it could be the Starter Relay



The Fuseable Link on the Battery Positive Cable, if you accidentally disturb this, then the Engine won't Crank!

The Starter Relay as Ecb Jag says is the Big Silver Box type relay just by the side of the Master Cylinder Actuator Brake Fluid Reservoir

In this Photo of a (UK) XJS V12 its the one with the little red label on in the Corner



The XJS V12 Starter Relay is over in the Corner by the Brake Fluid Reservoir with the little Red Label on
(for identification purposes) near that black cable

 

Determine if the clicking you hear is the starter solenoid or the starter relay. The relay is located under a black plastic cover on the right side of the engine bay near the hood/bonnet latch. It is larger than a normal relay (rectangular silver casing). Even if the relay is clicking verify that it's sending power to the starter with a multimeter.

Also, get a good battery that is a known quantity. Jumper cables can have all sorts of ill effects on the jag's already fragile electrical system. Attempting to diagnose without a good, strong battery is going to have you running in circles. Heck, that could be your whole problem. The V12's a big lump and it takes a LOT of current to turn over.

Finally, it might be necessary to turn the engine over by hand with a breaker bar to make sure it's not seized. Just DON'T turn it the wrong way even a little, as you'll almost certainly break the timing chain tensioner.

If the starter turns out to be the issue, there are many good threads already with detailed instructions. Just be warned that it's a bear of a job. So rule anything and everything else out first.

 

I know that on my 93 one of the main issues was the rotary switch on the trans (neutral safety type switch) one of the traces inside had burnt through and it just happened to be one that showed park and neutral, so it wouldn't let it try. Just another possibility

 

Thanks for the valuable information! Have a new battery for it and checked the wiring. Cleaned the connectors and it cranked right away. Briefly started with a little bit of starter fluid but couldn’t keep it running. I noticed that the fuel pump wasn’t turning on with the key or ignition. When I checked the relays one had some broken stuff in it rustling around when I gently shook it. Would I be able to easily replace this? Also would the fuel pump relays from other models of the same year work? Thanks again for all the help!

 

Hi XJS87

Replacing the Fuel Pump Relay is dead easy, as the Relays are behind a Plastic Cover in the Boot/Trunk by the Gas Strut Hinge

The Fuel Pump Relay is in the Black Holder and the Main Relay with the Red Stripe is in the Red Holder

These Relays are NOT Interchangeable with each other, as the Main Relay in the Red Holder is fitted with a Diode while the Fuel Pump Relay in the Black Holder does NOT have a diode

Also BOTH Relays need to be working, or the Fuel Pump Relay will NOT work

So change the Fuel Pump Relay First (The One in the Black Holder without the Diode that does NOT have the Red Stripe)

And See if that Fixes the Problem and Relays from another XJS should work as long as its got the same Values written on the side

 

Alex gets the vote of the day.

The Fuel Pump Relay is a STANDARD 5 pin relay, and has 2 (two) "87" terminals as part of the pin arrangement.

Some of the same looking relays have "87a" and 87b". DO NOT fit them please.

When you look at that Black socket, you will see an Orange wire. This is the EARTH for that relay, and is controlled by the ECU, and its internal timer. If, after relay replacement, that pump still does not work there are a few other things to check BEFORE throwing $$ at it.

The Main relay, RED socket, turns ON the fuel pump relay, and heaps of other things, so as Alex said, the Main relay must also be working.

Some of that info is in my sticky at the top, NO start of a V12, and goes through many things.

 

Hi Grant

Without you and 'Greg' my own Car would still be in the Garage!

So I am in the Process of building a 'Shrine' to you both

 

HAHAHAHA.

Beer in mine, no idea of Greg's liquid passion, YET.

 

I am just the apprentice, OB! As for the shrine, place a drop of 98 octane in a magic lamp and say the spell to get it to always keep my car 7/8th full!!
Cheers
Greg

 

Hi Greg

Consider it done!

 

JD for you Grant (Obvs)

Fine Wine for Greg

Prosciutto for the GF

And as for me a nice Cup of Tea and a packet of 'Jammy Dodgers'

 

got really fortunate with this project recently. The local scrapyard had an old xj6 that’s the same year as my xjs and it had plenty of parts that I could get off of it. Got the relays and fuel pump off it. Swapped them onto my xjs and she started and idled really well. The throttle response struggles however. Could that possibly be the fuel injection being clogged up from sitting? Lot of grey smoke blew out the tailpipes at first but then settled down. The left fan for the radiator also did not turn. Is this normal or should it be constantly running with the engine? Thanks again for all the help! Wouldn’t have her running without it!

 

Stale fuel, perhaps?

Poor throttle response could be a number of things. Faulty Throttle Position Sensor, throttle linkages not properly set, throttle bores dirty, retarded ignition timing and/or inoperative advance systems......and that's just off the top of my head.

Pick a jumping-off point and dig in! Lots of people here will help. Most of these old V12s have a laundry list of faults that need correcting. You just have to slog thru 'em.

On your '87 the aux fan should come on whenever the climate control system is 'on', regardless of mode OR when the coolant temp hits xxx-degrees. I wanna say 94ºC but I might be corrected on that detail

Cheers
DD

 

Awesome, let’s hope its stale fuel cause it’s been sitting for a while. It didn’t get rough just was a slower response. Thanks!

also I noticed that there is no brake fluid in the reservoir. Is there anything I should keep in mind while bleeding the brakes on the xjs?

 

Your '87 car should be "Pre-ABS" so bleeding the brakes doesn't require any special technique. Pretty much like any other older car.....difficult access to the rear bleeders being a bit of a bugaboo.

I wouldn't be a bit surprised if much (or all) of the braking hydraulics are original. And sitting for fours years can be tough on any brake system. I can almost promise you have more work ahead of you in this area.

Cheers
DD

 

It’s going to be an adventure, that’s for sure! But I’m excited about it. Enjoy the little progress each day

 

Yes, renew the flexibles (2 at the front one at the rear).
Renew the master cylinder or re-rubber seal it. The seals (and your brakes) will fail as soon as it does any real work.
In your position I would renew the pads and if at all worn or badly pitted with rust the discs too. If they are not rusted, no need.
There is a good chance the calliper seals will have gone too, or that the pistons are rusted, so be prepared to check them carefully after a few drives, if you do not renew them now - which I would say is the safest option.

 

Might want to consider cleaning the auxiliary gas tank and filter as well. Replacing the main fuel filter (behind the spare tire), cleaning/replacing the plugs, upgrade to 8mm plug wires, replace all fuel hoses on the fuel rail. Lubricate the distributor shaft.

Drain, fill, and bleed the radiator coolant system.

All these, and many more, I learned from the guys on this forum.

 

Thanks again for all the help! Haven’t had time to completely clean the tank out but I did drain it and put new fuel in. Made a world of difference for throttle response! However the engine starts to lag when it reaches 5000 rpm. Any idea what that might be? Thanks!