No start of a HE V12.
 

After reading many threads over the years about V12 engines that will not sart for what many various reasons.

Sooooo, I wrote up all the reasons I have dealt with over those years, and here it is.

GGG will "sticky" it for all.

Attachment 144082

Obviously there will be someone, somewhere, with other issues, and the Forum will sort that as we always have.

Very useful 'Grant' that helped me out a lot.

Many Thanks

Great write up, thanks for sharing it and taking the time to write it up

Amazing amazing amazing!!!

Thank you very much,,, Mr. Grant!

No fuel = No start. I still've not been able to figure why I have power to injectors but am not getting a pulse. This helped clear up LOTS! - I think,,, lol

Many many thanks.

Very informative. Thank you!
I once had an issue with engine cutting off and starting back every one second. I noticed at that time that internet is missing such summaries

Thank You Sir, I just bought an 89 XJS rust bucket, to repair the burnt wiring. I found on my 89 Jacobra. Mine had an engine fire, and burnt the wiring under the dash as well as the heater A/C assembly. So I got lucky and found another for parts. It was a running driving car 5 years ago, then he parked it to start a restoration. Well life got in the way, and he started it every couple months. Then one day it ran out of gas, and wouldn't restart. Darn the luck. So I bought it and intend to sell the engine and trans, but they will be worth a whole lot more, if someone can hear it run. So thank You very much. I read your guide beginning to end. I'm an ASE master technician, but I'm a Ford guy, and Jaguar's speak a little different language, and I sure don't want to pet the Kitty backwards!

Jack

Then ya gotta sort the "Aussie Speak" to get to the core, apparently we talk funny?????

Wll done and good luck.

I don't think you talk funny at all. I'm also a senior member on the "Mach 1 Club" as I also have a love of Mach1 Mustangs. We have several members there from Australia, and I'm very good friends with most of them, and enjoy exchanging with them. Yes there are a few words, that are different, but the thoughts, and attitudes coincide very well with mine. I saw a picture of a couple of the guy's had posted, and I said Wow, "You Guy's Look Just Like Us"!!! LOL. We all had a good laugh. I guess I had the Idea you all looked like "Mick Dundee"!

Jack

I've skimmed through your article but hoping you can help me a little more direct...

My grandpa and I are fixing to life an '85 XJS double 6. We checked the ECU and are getting continuity throughout the system, pulled the plugs to check for spark. SPARK! With 5 plugs out the engine turned over before we quickly shut it off (mostly due to surprise!), put the plugs in...nothing. Tried to turn it over again and life! for a couple seconds. My 81 y/o pops thinks that it is either the coil (we have power to the cost, but possibly not past it) - the coil passed his test to see if it worked before we put it back in the engine. OR he said it could be the ignition trigger.

Any help would be fantastic.

PS - the car was a barn find, in really goo condition but mice did wreak havoc in the engine bay by chewing wires, and as we all know the XJS is a wiring nightmare.

James

Hey HJ....

If you havent already, pull the distributor cap and see whats going on in there. Replace at least the rotor arm and clean up the insides. Clean up coil plug-ins. Check to see that the flaps on the intakes are not gummed or corroded shut wiggling by hand. Check all all all vacuum lines,,, at least the obvious ones. If there is an AAV Aux Air Valve (its on the BACK LH or drives side coolant rail alllll the way towards the back),,, its a silver aluminum gizmo with a really short black bendy 1 - 1 1/2 inch air hose coming off the top going into the back of the LH intake manifold and fed by a 1 - 1 1/2 inch black rubber tube plugged in and up under and behind the LH drives side air filter --- spray a bit of lub down in there to make sure its free'd up somehow. Be careful not to crush and crack the old hoses!!!! If it seems impossible maybe leave it be... How the AAV mech works is a pian to describe...

There is also a resistor pack on the front passenger side just behind the RH head light area BUT under the hood. Its mounted on the front inner wall under the hood and all of the fuel injectors wiring run thru it. Unplug, clean, plug it back - clean all the plug ins associated with it right up to the fuel injecctors. Also in the extreme heat of the "V" are the where jaguar ran the injector wiring. Check them as best you can or maybe pull themout of there and run them along the top for now. I did. Check for mice having made lunch, cracked and shorting lines AND check and double check that the are NO leaks or cracks in the fuel lines. All in the same general area. A split fuel line and shorting fuel injector wiring on test start (if there are fuel puddles) will not make for a happy test start. Especially if you are still inthe barn!!! :(https://cimg2.ibsrv.net/gimg/www.jag...6666fd92db.jpg

resistor pack for fuel injection
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AAV - this is a little different that what/how you might see in yours --- but its there...


Check the function or replace ALL (they are pretty cheap) the coolant sensors on the coolant rails just behind both thermostat housings. Check and clean the connections, at least. These sensors are important in the starting after a long sit.... Start cleaning and checking every single ground point you come across and your pops can find and,,, I liked this,,, be careful but unplug and replug every connection you see and come across, scuffing up the connecters a bit quickly (if possible) in the process if ya can... Yes, lots of electrics.

Also. I might add, rig something up and individually test each FInjector... Quickly apply voltage to each by just tapping maybe a 9 volt battery with wires to each. Listen for the "click"... I learned,,, when in the exact same position as you,,, that the FInjectors are tough little bugs and can be brought back from inner tarnish and gunk built up after a good long sit like they have had. Applying some kind of pressured solvent to the injector while tapping the electrode worked for me to free them all up. 10 out of 12 were not firing to open to supply fuel.

James,

That scary running when plugs are missing is normal, teh V12 is Female.

The few seconds running is classic EFI (Injector)( wiring loom failure, and the mice are to thank for that.

Some cars have 2 cold start Injectors, direct into teh inlet manifold, one each side, just on the inside of the throttle housing. Some cars dont. Jaguar messed with them throughout the HE model run. I remove any that I find, NOT needed, unless you live in the snowfields.

They squirt a burst of fuel as the starter is engaged, and that can give the running you are experiencing. Then, with the loom issues, the Injectors are NOT getting a pulse signal, so they dont do their thing, so the engine stops.

The shielded wire from the Ignition amp TO Pin #18 of the ECU is broken, mice, old age, either/or. That pulse is mandatory for injector pulse to take place.

The Injector Resistor Pack, located on the inner guard, RH side, just behind the RH headlamp bowl. Silver thing, about the size of a packet pf smokes, with a multi pin pug inserted from teh bottom. Remove that plug, CLEAN it and the receptacle in the Pack, then CLEAN it again, then replug. That is getting to be a very common fault with these now.

My gut feeling, the wiring is waaaaay past its use by date, and teh micve have totalled it. NOT hard to replicate, time consuming, HELL YES, but it will be needed sooner than later.

Spark plugs, NEW are needed, and gapped to 0.025". The HE with 12.5:1 compression ratio, OOPS, you guys got the poverty pack 11.5:1 engines, is NOT forgiving with plugs that are "so/so".

​​​​​​​I will PM you later.

I read through your article and had a quick question. While testing the fuel pump you said to check for battery voltage at the fuel pump. Did you mean I should have 12 volts at the fuel pump or does it draw less with just the key turned? I'm getting about 3 volts and trying to see if I just have a bad ground somewhere

Yes, and I did NOT state a figure, coz some people will have 11.8, some will have 12.2, and then go looking for something that is perfectly OK anyway. Around the 12V mark is what the pump is looking for.

Your 3V is NO GOOD.

Couple of things:

Earths, as you mentioned, and the MAIN in that area are beside the battery, and there are many down there, sooooo, remove, clean, clean again, grease the area (just a smear), and refit and tighten suitably.

The relay is tired. The pump relay is in the BLACK socket, and is a STANDARD 5 pin relay, with 2 #87 terminals, meaning NO "B" or "A" in the schematics. The pump draws approx 6amps +/- whatever.

The ECU earth circuit, which is NOT via the casing, is hissy, so EARTHS AGAIN come into teh discussion. The ORANGE wire of that relay IS the earth, and controlled via the ECU.

Ignition switch electrical section is DIRTY, and a simple test is to turn ON the Ignition, and probe the +ve terminal of the Ignition coil, should be 12v or close. If it is, then the switch MAY be OK for now. If its as low as the pump +ve, then that electrical section needs to come out, be opened up, cleaned and relubed.

My bet is BAD earths all over the car.

Hi Grant

Had my first no start issue with the mistress about a week ago ....was going to take her into the office one morning and she turned over OK but would not start.

worked through your check list and it ended up being the condenser in the ignition amplifier. I checked the black box as per the attachment ... it was OK ...then removed the condenser .....also attached ... replaced the amplifier and boom .....!!!!!! ..... she fired straight away .... sensational ......!!!!!!!

Electricery is really not my gig so your easy to follow instruction were fantastic ... and saved me a few $$$ as well.

many thanks ...all good

Darren


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Darren,

Thank you, and glad I could help.

Now turn those $$$ into beer and we are all on a winner.

I know it is 2020 but the old girl has been dead in my driveway since last summer I am going to run though the Steps. I feel like I found the The Gough Map I don't now if I can fix it but at least now I know where I am going. Thank you Grant Francis

D!!!
You can fix it!!!
Report back!

The main thing to remember:

These are NOT complicated cars, so DO NOT over think things.

Work to a SYSTEM, swapping all over the place will not help at all.

The many years of neglect, near enough attitude, etc etc, is now at your feet, and it may seem daunting, it is not, especially the V12, so simple in the real world.

ASK QUESTIONS, and always remember there is NEVER a silly question.

Good luck.

Further to Grant's excellent article, I've recently found the charts below from my original Jaguar 1979 pre-HE owners handbook. They may be of help to those running a very early XJS.

Paul

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