Gentlemen,
I recently acquired an abandoned XJS convertible from Tucson which had a "small fire" under the dash. My first goal was to get it running and I think I am very close except for a few "loose ends".

1. Does one of the vacuum lines from the distributor with the air filter attached really go nowhere?
2. There is a component attached to the A/C. Is it a fuse of some variety or a connector???
3. The Heater Water Valve needs a vacuum hose but I don't seem to have enough connections, pls advise.

Thanks, Mike
PS. I tried to attach photos but it wouldn't let me.

 

Yup. It's left open-ended. Usually it's wire-tied to the engine bay brace, where the brace meets the fender, LH side

Where on the AC? Without pics you'll have to be a bit more specific

The vacuum hose to the heater valve ultimately goes into the cabin. I'm not sure if you'll find a connector on the engine bay side of things. My memory is foggy on that. There might be a 'pass through' nipple but I'm not sure. If so, it's probably down low in the engine bay, sort of in the foot well area. Others will chime in with better info

Cheers
DD

 

The vac hose for the heater valve comes through a plate in the engine bay where the pedal box would be if the car had the controls on the other side. There are two hoses coming through: one to the heater valve, and one going via an inline non return valve directly to a spigot on the end of the A bank inlet manifold. The one that goes direct to the manifold charges the vac reservoir just under the plate, and the one to the heater valve goes into the cabin to the HVAC unit.

 

 

Gentlemen, thank you for the quick reply which is greatly appreciatred.

I tried to add the photo of the A/C harness component in two different ways so there may be 2 photos of the same thing.

Since I have the entire interior pulled apart the hose to the heater valve will have to wait, now I know.

Best regards,
Mike

 

Hi dmichael

A 1989 V12 should be a Marelli but if it was at the 'Cross Over' it could be a 'Lucas' could you confirm that your Car is a Marelli, so that we can help you more if need be

 

It is Marelli.

We tried to start the car this week and confirmed all the bits for the fuel system work. It appears I do have a few leaks to fix.

We were not able to get any spark … I have new plugs, new wires, new rotor and new cap. I'm working my way back according to the diagram shown. Everything is hooked up correctly to the Power Modules and beyond to the distributor.

My question, Is the lack of a spark due to lack of other connects I have not made yet? What are the chances that there is no power to the ECU?

I'll look for the ECU power source and check it and insure highlighted connections are there.
Thanks for the hekp.

 

Hi Mike

Just to give you a double Check:

The Lower Coil (The Red One) goes to 'A' Bank

The Upper Coil (The Yellow One) goes to 'B' Bank

If those are connected the wrong way round then you won't even get a Spark

The Ignition Amplifier/Power Modules that sit on Top of the Front Closing Panel need to be bedded down on top of their Heat Sinks with Thermal Paste, same as you would use to bed down the CPU in a Computer

While not doing that shouldn't prevent her from Starting, the Thermal Paste will stop the Ignition Amplifiers from overheating and burning out $$$$

One of the most common causes of 'No Spark' is 'The Crank Position Sensor' (Cps) at the Front of the Engine as I'm sure you know

Also make sure the Plug and Socket to the Silver Box (Resistor Pack) near the Headlight Nacelle is Nice and Clean so you have a good connection (see Link below)

Trying to Start my V12 XJS after a 14 Year Layup and managed to get her going!

In the event that none of that works then it Could be the 'White Shielding Wire' aka 'The Dreaded Shielding Wire!' that lays in the Vee and gets Fried which is a Coax Cable (A White Coax Cable) that is joined by the Left Hand Air Intake of the Engine and 'If I remember Correctly' goes to Pin 24 of the ECU

So you need to make sure of the Continuity of there being no breaks in this Wire

Where one of the ways you can do this, is to get a long length of Coax Cable the same as you might use for a TV Ariel and go from the join in the Engine Room and then Run it right round the Outside of the Car all the way to the ECU which I think is Pin 24? so when you find it let me know as I am doing this from memory with no diagram

One thing you need to bear in mind is only earth the Shield Wire (Part) at the ECU end rather that at both ends or you may find it won't work

If I have mismemorized this, someone will jump in and let us know!

Good Luck!

You seem to know what you are doing

Alex

 

Look at the top of the Classics X27 XJS Forum, and you will see a posting "So you have a HE V12 that wont start". Read that, print it out, and follow it. When finished, it will either start. Or at least you will know why not. LOL! Hope it helps. It did me. And like you, I know what I'm doing. But the Jaguar is a little more complex in it's ignition system, then an old Ford or Chevy.

Jack

 

Double Check:
1) Unfortunately I have (2) Red seals / grommets ... but I think I'm good. (see pictures)

The Lower Coil (The Red One) goes to 'A' Bank
My Power Module A has white, slate, slate/purple, black and a white wire.
Input to coil A should be white, white / brown, and white brown which I think it is.
Coil A goes to the center of the distributor.


The Upper Coil (The Yellow One) goes to 'B' Bank
My Power Module B has white, green, green/purple, black and a white/black wire.
Input to coil B should be white, white / black, and white / black which I think it is.

2) Heat Sinks with Thermal Paste look good.

3) One of the most common causes of 'No Spark' is 'The Crank Position Sensor' (Cps).
Well, this was one of the wires the mice ate and I tried to fix it. I pulled it and tried to test it by moving a drill pit past it and I might have seen a 20 mA number and I saw that it should be in the 400mA range?? In any case I ordered a new one.

4) The Plug and Socket to the Silver Box (Resistor Pack) near the Headlight Nacelle is Nice and Clean so you have a good connection.
I cleaned the pins and sockets with carb cleaner and Qtip cotton.

5) It could be the 'White Shielding Wire' aka 'The Dreaded Shielding Wire!' Which is a Coax Cable (A White Coax Cable) that is joined by the Left Hand Air Intake of the Engine and 'If I remember Correctly' goes to Pin 24 of the ECU
Can't seem to find it ... Where does the white shielded wire come from?

I started to use the information for "so ya got a HE V12 that wont start" but it started me at the "coax from the ignition amplifier firmly bolted to the top of the LH inlet manifold" that's not where they are for the 89 so I'm going to open all the wiring looms in an attempt to find up where it starts.

 

Hi Mike

Here is a Pic of the White Shielding Wire on my 1990 XJS V12 where that thin inner strand goes all the way to pin 24 of the ECU

Although the Coax Shield of this is only earthed at the ECU but not in the Engine Room

On a Lucas Car that Wire would go to a totally different Pin

I had a look on my 1989 XJS V12 and I couldn't see that White Shield Wire either! as it is very well hidden

So might be better to first try the New Crank Position Sensor




Alex

 

got it...I checked continuity from the plug to the ECU on pillar A. I also check continuity of the white wire from A pillar ECU to the ECU in the trunk and I'm golden. Now just waiting for the new sensor to show up.
I also found a wire for the flywheel speed sensor and I have continuity with the ECU at pillar A. I guess I'll go hunting down under to find the actual sensor and check it out.

Thanks for all the help

Just one final loose end … do you know where the following connection goes?

Mike

 

Two spade terminals on the front side of the air con compressor.
Rob.

 

You can seen the connection just behind the compressor pulley.
Rob.

 

Gentlemen,
I have replaced the two sensors that were in really in bad shape and have move on to the "So Ya got a HE V12 that won't start" write up / checklist.

I didn't get too far past checking the fuel system 1) the pressure at the LH fuel rail and 2) the fuel flow before the fuel pressure regulator.

1. Initially the pressure went to 40 psi at the fuel rail and then I heard a "click" and the pressure dropped.
2. The fuel started to flow nice and then I heard the same "click" and the flow shut off. The write up said "the fuel pump will activate and run for a few seconds, in that time the fuel will gush for a few seconds."

Please advise, is that the normal operation?
Having said that I also observed a spike when I rotated the throttle cap stand. It started at around 300 mV and increased nicely and then there as a 1.2v spike. How does that affect the starting of the engine and can that be tuned out or buy replacement

Thanks,
Mike

 

Hi Mike

The Fuel Pump will only run for about 3 Seconds at every Actuation (on/off) of the Ignition key, this is perfectly Normal and is exactly what should happen and is also
a good way of Testing the Fuel Pump Relay: So you sound good to go on all of that

Also you will notice a 'Spike' as you Rotate the Capstan as the Injectors open and you should also hear them 'Click' so that sounds all good as well

Assuming that everything is plugged in, it does sound like your problem could be in the 'Spark Department'

Have you Tested for a Big Blue Spark?

No need to take one out of the Engine, you could Test it with a Spare Plug on one of the Leads

Could be the TPS Throttle Position Sensor (Greg and Grant) are the Experts on that

Here is a Short Video of How to Test the Fuel Pump and the Fuel Pump Relay (Link Below)

Testing The Fuel Pump and the Fuel Pump Relay on an XJS V12

Good Luck

Alex

 

Alex,
When you say Big Blue I don't think I'm there.

How blue is blue … a lot more than this?

Mike

 

Hi Mike

Hard to tell from the Photo but at least you've got a Spark (clean all the Earthing points in the Corners of the Top Closing Panel over the Rad) where several Wires are held by a Single Bolt as that might make a big difference (a known problem area)

Can you hear the Injectors Click when you turn the Throttle Capstan?

Have you tried a quick squirt of 'Easy Start' to see if She will fire up?

Could be the TPS of which I know virtually nothing, so hopefully 'Grant' 'The Wizard of OZ' will jump in

What 'Grant' doesn't know, you don't need to know!

Alex

 

Alex,
I cleaned all the Earthing points in the Corners of the Top Closing Panel over the Rad

Can you hear the Injectors Click when you turn the Throttle Capstan? Yes I do, I should mention that if I rotate the Capstan around 10-15 times there is enough fuel put into the cylinders to run for a few seconds. It just seems it's not getting gas after that. Is there a situation where the pump relay might not be activated when the ignition switch is in the run position?

Have you tried a quick squirt of 'Easy Start' to see if She will fire up? I tried using starter fluid and again it ran for a few seconds.

So I too am hopeful that 'Grant' 'The Wizard of OZ' will jump in

In the meantime I am going to review the circuit when the key position is "run" an see what the pump relay does.

Bye for now and thanks,
Mike

 

Hi Mike

Yes! there is a way that the Relay may not be Activated in the Run Position

Find the Orange Wire at the Fuel Pump and then Ground it

Then try and Start Her and this time if She runs, it could point to a faulty ECU or a faulty Fuel Pressure Regulator on 'B' Bank with a punctured diaphragm

First thing to try if She Starts after that would be a New Relay

Alex