Hi Vee

Yes that's the first thing I tried but getting the Injectors out looks mega complicated

 

OB
I had a similar problem with my xjs some years ago, but it cranked without the little 'catches' that you're getting and mines an earlier AJ6 engine.
Seems like a fuel problem to me.
Check if the plugs are wet after cranking as someone has already suggested, mine were ALL dry.
Mine displayed all the signs of a dodgy CPS which I replaced but it wasn't that.
It turned out to be a faulty 10 euro relay that supplied power to the fuel injectors/ems in the passenger footwell (UK car)
Took 5 minutes to fix in the end. Here's a link to the post on the jag lovers forum that follows my tribulations;
Good luck
https://forums.jag-lovers.com/t/xj-s...o-rpm/347483/2
https://forums.jag-lovers.com/t/xj-s...-solved/347486

 

Hi Paddy

I think I'm very close to solving the problem and what I found 'may' surprise a lot of people but no time to write it up right now as I've got to pop down the shops

Sorry to sound so 'Cryptic' but I want to explain this in detail

BTW Thanks for your help, something in the Link you gave me could be Plan'B' if Plan 'A' doesn't work

 

Inquiring minds want to know what you have come up with. Looking forward to your more detailed post on this problem.

 

Hi LuvmyXJS

From what I have just experienced, it looks as if the first 20L of Petrol, is nowhere near enough to Submerge the Filter on the bottom of the In-Tank Fuel Pump, in a bone dry Fuel Tank

As unless you are able to Calculate the Area of the base of the Tank and the Volume of Petrol that you are going to need to cover the Filter, then a certain amount of guesswork could be involved

And it looks like I guessed wrong with 20Litres!

Which I mistakenly thought would be more than enough, where in an ideal situation the Fuel Tank would be full enough, so that the Steel Band that surrounds the Fuel Pump is completely immersed in Petrol, to prevent any Petrol Starvation

So at another rough guess, I reckon that I am going to need at least another 20Litres of Petrol to make sure that the In-Tank Fuel Pump is fully submersed enough to try and Start her

With the 'Benefit of Hindsight' I could have worked out more accurately how much Fuel I was going to need, by Filling up the Fuel Tank with a 'measured amount' of Water, while I was Washing the Tank out although of course I never thought of that

 

Hi Paddy

Initially it looked as if I had the same problem that you mention in the 'Link' you gave me, as I was also thinking that it could be the immobilizer, as well as also maybe the 'Crank Position Sensor'

'With the benefit of hindsight', I don't think that the CPS was at fault as the Tacho was showing 1000 rpm when Cranking, the same as my New one now does

But then again just like yourself, I was also wondering if it could have possibly been the Immobilizer and I'm still on the Fence about that one, as I'm really not sure how it works because I can't find the Handbook

But the Car used to make a 'Bonging Sound' when I opened the door, except that now it just doesn't 'Bong' anymore! which could be good or bad for all I know (or in this Case, 'really do not know')

There seems to be a battery that goes into the Key but I don't know how to get that open, so that I can put a new battery in and that same key also has a Push Button

And there is also another Push Button on the Key Fob as well

Though if you have been following this 'Saga' everything seems to be pointing to a lack of Petrol in the Tank, as the 20Litres I put in, is really looking nowhere near enough, so I've just come back from the Garage

With another 50 quids worth and so we'll see if that makes as much difference, as it has done to the contents of my Wallet

 

my 93 xjs had similar symptoms. i replaced the crank position sensor and mass airflow meter and a bunch of other stuff before i figured out the signal to the injectors were intermittent causing my no starts. and most likely a bad ecm, at that point i built a 400hp sbc engine and swapped it into my car.

you can use a noid light to check to make sure that the injectors are getting signal.

 

That ring around the fuel pump has passages at the bottom to let fuel in. 20L is 1/4 tank, that's plenty of fuel. Lack of fuel to the pump isn't your problem. The sock on the pump might be dirty or the filter plugged or other things. As mentioned, crack the fuel line at the engine and run the hose into a bucket. Turn the ignition on and see of you get fuel flow.

 

Hi Jagboi

I know there are passages at the bottom of the Steel Ring in the Tank to let the Fuel in and the Fuel Pump and Sock on the bottom of the Pump are Brand New but the Fuel Pump and Sock are Not in direct contact with the bottom of the Tank

The Fuel Pump with the Filter Sock on the Bottom are Clamped to a Pole just inside this Steel Ring with a Gap underneath it, so unlike on a V12 which will run with only a gallon of fuel in the Tank (Because it has a Sump Tank)

The 4.0L Facelift Tank, does Not have a Sump Tank and instead relies on the Fuel Pump being clear of the bottom of the Tank, so that the Pump Sock doesn't continually get clogged up with crud

So before the Pump gets to suck any Fuel, there has to be enough Fuel in the Tank to cover the Sock on the bottom of the Fuel Pump or you will get Fuel Starvation

And although 20L of Fuel Sounds a lot, the Fuel Tank on a Facelift 4.0L is a lot wider than the Boxy V12 Fuel Tank

So 20L spread all over such a long and wide area, 'may not provide enough depth of Fuel' to Fully Immerse the Fuel Sock on the Bottom of the Fuel Pump

This extra Fuel needed to cover the Sock is a 'One Off' event, as once you are up and running, when the Fuel gets down to this critical level, the Fuel Gauge would show empty, even if there is some fuel left in the Tank

 

Hi Guys

I took out all the Plugs today and each and every one of them was really Carboned up, although I would add that She does run with a Tea Spoonful of Petrol poured down the Air Intake

Which seems to lead me to believe that the Spark Plugs are Sparking (or am I wrong on that?)

16mm Plug Spanner also did the job just fine, as none of the Spark Plugs were in 'Stupid Tight' @(Grant 'The Wizard' Francis)

'Paddy' No sign of any Relay in the Footwell by the ECU but I did find a group of 3 of them in the Boot/Trunk

One was in a Red Holder which I think was the Main Relay which Controls the ECU although it didn't have the expected Red Diagonal Stripe (none of the other Relays had that Red Stripe either)

The Middle one was Silver in a Yellow Holder which I think is the Fuel Pump Relay

The Third one was in a Blue Holder but I have no idea what that one is for

All of these were Super Easy to get to (NOT!) as I had to remove the Hydraulic Pump for The Soft Top (again!) and also undo all of the metal trim that runs down the full length of the Boot/Trunk

I know absolutely nothing about working on the AJ16 4.0L so any help and advice would be appreciated, as I would like to know my next move

 

New plugs for a start OB!

 

Hi Greg

Then what (lol)

 

plugs would be a good place to start they are certainly fouling. what is really strange looking is the black streaking at top of the plug socket on the outside ceramic insulator.

 

You'll find more on the X300 list, as the saloons have the same engine. These engines are very fussy about their spark plugs, use only the original Champions. I forget the designation, it's either RC12 or RC9. Use the plain copper plugs, no fancy platinum or other plugs, the AJ16 doesn't like them.

Black looks like it's running rich to me, and there are only a few things that can influence fuelling: Coolant temp sensor, air flow meter, fuel pressure, battery voltage and the ECU itself.

You should grab the electrical manual from JagRepair.com - Jaguar Repair Information Resource just to have. If you have an assistant crank the engine, put a long screwdriver on an injector and the other end to your ear. You should be able to hear them click if they are working. Try it on one of your other running cars to know what it should sound like, it's quite obvious. If the injectors are operating, then look at the fuel delivery side. If not then look at their power supply and the ECU power supply (thus the need for the wiring diagram).

Does your car have an OBDII diagnostic port? I'm not familiar with UK market cars to know if a 95 would have had it. The 95 XJ saloons did. If it does, you should get a good OBDII code reader that has datastream readouts. Then you know what the ECU is seeing instead of guessing.

Ignition coils are a well documented failure on these engines, read the massive thread on the X300 forum about them. If you need replacements, use nothing but the OEM coils made by Diamond in Japan. SNG carries them, I'm not aware of anyone else who does. Even if you splash out the insane price a Jag dealer asks for a coil it won't be an OEM coil now.

 

That's high voltage corona. Fairly common on plugs that have been in for a long time.

 

Hi Jagboi

Many thanks for that very useful repair link

As for the Coils, I had a look but couldn't see any reference to 'diamond' but are they the ones that are priced up at over £200 each!

 

Thanks for sharing the photos.

First off, you may have pulled out the original spark plugs that came with the car! There is a TSB that changes the spec for the plug from the RC9YCC plugs you have in the pics, to the hotter RC12YCC plugs. It's time to change them. Some people choose to go with NGK plugs, just remember you'll need to use the BRK5 plug, not the BRK 6 that is specified everywhere as an as equal. It seems the BRK6 is equal to the RC9, then Champion numbers get hotter as the numbers get higher, whereas NGKs get hotter as the numbers go lower.

As a sidebar, the corona is indeed normal. There's a TSB confirming that as well.

Your car has dozens of relays, all over the place. I believe the relay that Paddy was referring to is above the (USA) passenger footwell, and below the airbag. You'll have to pop open what looks like a glove compartment. It's really a relay and fuse compartment!

When you pop open that compartment, you should find two light blue relays. The EMS relay is the one on the left (white base), the ECM controlled relay is on the right (blue base).

You'll find more relays if you pop open the compartment under your steering wheel, in the trunk, where every piece of trim you remove will expose more relays. There are several under the hood as well.

You may want to update us with whats been done, since you've had a bunch of suggestions, but I'm not sure what you have followed up on and what you haven't. I don't want to repeat any of the suggestions, if they've already been chased down.

 

It looks like SNG in the USA has them, not the UK branch. https://www.sngbarratt.com/us/#!/Eng...8-617ea71443cb About £80. Certainly ask at the UK branch, they might have them, I don't know
Part number is LHE1510AB# (the # is important, that means an OEM part, not aftermarket). In the big thread on the X300 forum SNG USA says they guarantee them for 3 years.

 

Hi Vee

Cheers!

There are Relays all over this Car as you say, its finding them that's the big problem so I'll have another look under the Glove Box where I also found lots of Fuses and all of those were Ok, as were the ones in the Boot/Trunk

Also Thanks for the 'heads up' on the Change of Spark Plugs

But before I go and Start to throw anymore money at her, as She didn't need a New Crank Sensor, I cleaned up the existing Plugs RC9YCG in my Ultrasonic Cleaner and they came up like New!

So I am going to put those back to see if She will Start and if She does then I will go and get the hotter ones that you have mentioned RC12YCC

I've also done a Video of Cleaning the Spark Plugs in my Ultrasonic Cleaner, which I am going to put up on my 'Cherry Blossom' restoration link and when I do, then I will add the Link to that Page here.......Cleaning Spark Plugs In My Ultrasonic Cleaner

Don't worry about duplicating what I might have done, as its always good to have a reminder

Thanks for your help

 

Hi Jagboi

I'm really hoping I don't need New Coils as they are very expensive, especially the OEM ones at £200 each!

So I will try and test the Plugs first and hope that we get a good Spark