The same thing was said about my XJS. It took me one Saturday to get it running! :-D

The Jaguar v12 really is a very well engineered unit. Powerful and smooth. Very underrated engine.

Very impressive, your knowledge of these models is comprehensive and highly commendable, a thoroughly enjoyable video as always, look forward to the next one 👍👍

You really are the aficianado of V12 's Adam and patience really is a virtue ! Well done !

Man, that was a journey! Glad you made it!

WOW - 26:48 - A Running Engine!!!!!!!!! You are so methodical, rooted of course, in your knowledge of these engines, that you knew you'd eventually solve the riddle!

Great to see another one back on the road ! With that era of fuel injection / engine management there are only a few sensors and inputs controlling the system, whether it’s a Jaguar V12 or my 1994 Fiat Tipo 1.4 i.e. with a Bosch Mono-Jetronic unit… the temp sensor and wiring can really screw things up.

Well done!. I see so many v12 Jags here in Canada dumped because no one can get them going. Also people commit heresy and swap the motors for small block V8's rather than take the time to track down the issues.

The music for the title sequence is mind-blowing

Nice to get it working, always a good feeling, well done! 😀👍

Greetings from Australia Hi Adam you are a genius I have a similar issue with a friend's car will let him know Thanks Rob

'The wiring here is quite special'. Brilliant comment! Well done Adam.

Great troubleshooting Adam!! These types of videos are always very helpful.

Well done that man.

I am very impressed with your ability to get those V2 running. I have a 89XJS convertible version 12 that hasn’t run in over 20 years. Walked away from it for a year now after trying to get it running but watching your videos I’m getting encouraged to get back into it. Thanks for all your help. I only wish you were in California.

Great troubleshooting! I enjoyed watching you go thru the process to find the problem.

Well done Adam very knowledgeable video keep posting these love the breakdowns and your great investigative skills

Nicely done sir! I personally love this type of video. Keep up the good work.

Great video. Love your common sense diagnostic process. I learn a lot from videos like yours! Thanks!

Excellent video, very interesting thanks Adam

Good day Adam and we'll done.Glad that it is running again.And all the unnecessary headaches and wasting of time due to people didn't do a proper job .Luckily we can learn from and with you.Have a blessed day and good luck with the rest off the other issues.

I love your style - so calm and methodical - and I shared your joy when the engine finally burst into life. Brilliant video. Thank you.

Well done, Adam, Great diagnostic work.👍

Nice video and nice job Adam! I can really relate to the situation as I just got my 40 running with similar trouble shooting...measuring, jumping relays and what not. What a great feeling when you find the fault and it fires up! I'll try to visit you some time, would be nice to meet and to see your shop/Henrik, Halmstad.

Excellent work Adam :) top job mate

Well done Adam. Very interesting to watch. I would have been well and truly stumoed with that on, my knowledge of car electrics is very limited. The greasy bits I can manage but the sparky bits, not so much. Good job.

I got an 86 xjs im currently working on thats doing similar things, had it running somewhat then have nothing. Hard to find information on it, this has given me a great starting point thanks for the video

very well done you kept at it and you came out on top loved the video see you in the next video awesome job

fantastic work

u identify the problem within the first min of the video. Great info. I hav the same only not convertible. There was an engine fire so i hav removed everything on top of the block. Now lookin for a donor motor and harness to revive it. It has 43xxx on it. Found it in a field.❤

I remember your 26:49 moment well after going through all the same misery as you did. Mine was just an o/c coolant sensor in the end and it ran with a resistor jammed in the connector so I had a bit of an easier life.

Good one Adam, I hope that you charge the owner well for all this work finding the bodged wiring.

Great detective work, this is just the sort of fault finding to watch, listen & learn ready for the day you need it, maybe on a Jag but relevant to many other vehicles. Thanks. Allen

Good job! Well done! Nothing like the feeling of an engine coming back to life after spending so much time on it. I had an engine once that started but would not run properly when it got warm. It was a carburetor engine and I failed to notice that there was a little lever that had to engage with the choke when the air filter housing was replaced. Yes it was a Ford 😀😀

Wow they could be really stubborn. I just bought one a few weeks ago and thank God I bought it as a running V12

Well done Adam great job .

Excellent diagnostic work and perseverance , if you can get an old Jag V12 running smoothly you definitely are at the top of your Trade

Fantastic work really interesting.

Good job. The only suggestion I might have made was to early on try some starting fluid w/ the intake filter housings off (proof of life/ignition), and when cranking that much, dribble a little oil down the spark plug holes at some point for the rings/dry walls.

Brilliant find !. I had a very similar problem on an MGF (year 2000). Someone had unclipped the wiring loom when they changed the head gasket. The engine would start OK but the idle speed was occasionally erratic, climbing to 2000 RPM with the engine fully warmed up. The fault would appear now and then but no pattern to it. The loom was moving around when running over rough road and this would disrupt the connections to the ECU which would assume a default running state. It took me five months to eventually find what the issue was !, courtesy of traffic humps on the road where driving over them produced the wobbly cables to play up.

I love these V12 old Jags. I keep seeing them for a good price and its so tempting to want to get one.

God bless you and kudos to you oh, you are an awesome dude with a lot of patience😊

Heroic effort, ultimately rewarded. It used to be sufficient to check the primary sources/circuits; Gas, Air, Spark, but now there are all the extra control circuits. Are the sensors correct, are the messages getting through, is the control unit still awake and sane? Asking the owner what he had "fixed" between the time the car ran and when it didn't might have saved some investigation. As you know, when systems mysteriously stops working, the first thing to do is to get an honest answer to "What did you just change?" Clearly, you've found the answer, but while you were looking I wondered if it was possible for injectors to become "mistimed", i.e. to squirt at the wrong times. That might produce odd results.

Congratulation, Adam. Always a tricky thing to troubleshoot cars with "repaired" cable harnesses. Jeez... what did the previous owner do? Patchworked cables are always a bad idea. Good to see that the XJ-S is back on the road. Christian

when jags flood out, i have a "special fuse" for the fuelpump that i use to get them running. it's a blown fuse with a switch across it, spin over on full throttle [with the pump turned off], then when it clears + starts to rev up, flick the switch on. works a treat on the later [2000 on] V8 versions jag wiring used to go brittle with heat in our cold, damp climate in blighty, stands no chance in your neck of woods

Really enjoyed this episode.

Yay, it runs! It's starting to be the "Living with a V12" channel.

Such a mystery thriller, ;) Always fun to watch

I had something similar 30+ years ago on a 1976 car. It had been colour changed from lilac (rare on an XJ-S) to Signal red and when they took the engine out to paint the bay, they chopped the loom and reconnected each wire by just twisting and black tape. Occasionally the car would hiccup as a wire flexed. So, the loom was unjoined again and a proper connector plug fitted. The car lived in the UK and Hong Kong. It was in very good condition - where is it now?

Determination will always win. Well done.

Well done!!

I had a 73 xj12 that had the same problem , finally got it started but it didn’t wanna rev up at all - these engines are glorious when they are running well but an absolute SOB when their not!

I can remember a (Chrysler) valiant (slant six) which had an automatic choke, which used to 'flood out' with fuel if it did not fire immediately. It was then to manually take the choke off, and crank with a wide throttle.. The vacuum line has a 'choke unloader' from the intake manifold which takes off the choke as the engine runs, but it seems with excessive cranking when cold affects firing ability drastically (too rich), and you had effectively found 2 issues (no temperature sensor connected to ECU) and the vacuum line to the ECU. The need to clean the spark plugs was a good idea, as the engine oil (diluted with fuel) is a good insulator, inhibiting a spark for ignition...

I have one of these and it won't run properly, seems lean on the left bank. Your videos are so informative, thanks so much for sharing Adam!

We had one of these which started fine but as soon as it reached temperature, would splutter and die. Earlier than yours a pre HE. Beautiful car.

Awesome Adam

Thanks,great video Made my living repairing Jags(only Jags for 10 years, XJ6 and XJS ) for the drug boys(not only lol) of NJ NY PA, in the 80s and 90s,could repair them,hundreds, with my eyed closed,never ever,missed one; 25 pct of my work was SBC conversions,(made my own motor and trans mounts, mail ordered them out too, Hemmings..)with the 700R4 trans,manual command of the converter clutch, BEST CARS IN THE WORLD then; back home in pos portugalnow,but the INjustice system here sucks big time avoid

I'll just say, a few observations for others looking for solutions with a no start situation on a v12 - be careful, hesitant, at running a starter on a v12 as looooong as you are with a car that won't start. It's high amperage and the bits get really hot. Can fry a starter. Also, there should be no need to go wide open throttle at start up when looking for signs of life. Maybe 2 pumps or three with key at ON, then turn key with no peddle. Car should try to fire with very little gas. Also, the v12 is terrible about recovering from FOULED plugs. They basically will stay FOULED until they are removed and cleaned or replaced. 1 or 2 fouled plugs make a big difference in running and with all the fuel being dumped into the cylinders (wide open throttle point above) they will go sour again at next attempt. After a problem like this it is worth it (and a hassle because some of the plugs are tough to get to) to clean them ALL. And maybe even cycle the engine quickly with all plugs out to clean the cylinders. Great video. I don't mean to be a PITA, just making some observations.

19:20 haha, have a sleep man, what a troubleshoot so far ⚙️🔧😁👌🏻 26:30 such a great moment when you got 10 sparkplugs out and made sure to 'clean' the cilinders, after that it directly ran! Wow amazing troubleshooting really interesting 🙌🏻🙌🏻🙌🏻⚙️🔧⛽

done good

Hi adam!, excellent video for diagnostics i've got a xj12 that isn't running it did run before. i've replaced the fuel pump and the fuel pressure regulator on the right bank as it doesnt get any fuel there, cranked it alot but it doesnt want to start, it looks like the right bank isn't getting a vacuum going and doesnt suck enough air in. do you have any idea what it might be? i think the fuel pressure regulator vacuum isnt working but cant seem to find out why. and why does the left bank work but the right doesnt. I hope you can send me in the right direction, Kind Regards Roelof

Great video. Couple of comments I would make however (ex Jaguar tech UK). Don't guess.. test. Don't swap out parts.. test first. A car like this that's been standing will have a high oil level reading due the fuel injectors leaking into the bores and washing past pistons into the sump. Always best to change oil first because running an engine even for a short period can cause damage to cams, bearings and seals. Also, get a wiring diagram of the vehicle you're working on, especially one that can give you correct readings so you don't have to guess. The V12 looks at first to be a very complicated engine, but it isn't. Just take a cool a methodical approach to any issue and you will soon find the problem. I must admit that the first thing I look for with any running issues is "amatuer tampering"....as you eventually find in the video. Well done. These are beautiful cars and deserve to be seen more often.

Man how lucky am I to have bought one that starts instantly🎉

Good job that you got the car startet (y) And good thing that you found the bad wire and connected it up again. BUT... Fiddling around with a lot of different cars from all over the world the first thing I look at if it is an English or Italian car, is faulty wirering ! I can not for the love of god (or whoever you can think of) think of worse cars when it comes to the electric system and especially the wirering. Bad connections, wire dimensions are out there (always too thin) wirering are made from substandard cables that go brittle and discoloured after a few years and they are often made by hand and it looks like the workers who do them, are drunk or just don't care that they do bad work. Look at German, Swedish, Asian and even French cars and the do not have those problems. You can often fire up cars that has been standing for years without any problems at all. I hope that you have swabed all the wirering you showed us ind the video. I would if it was my car...And I would change most other wires in the thing. If the cables we see look likes that, what about all the cables we can't see ? I would be seriously afraid of fire do to the bridle wires. And just a question: The first thing I noticed was the seemingly pour power on the battery. Is It normal that it sounds like it is just about to give in ? I know that it is a big engine and it demands a lot of power to turn, but so does V12 BMW and Mercedes. I have been working on both V8 and V12 Germans (and one V10 BMW M5) and I have never come across such a pour powered battery on any of those... Make me wiser :-)

Damned good job!

Great job like me never give up

You are really clairvoyant about Jaguars. Is your last name Lyons. 😀

Does this car have a obd port .. or a wat to scan the check light ?

Impressive

Adam awesome job isolating the problem. Electrical tape unfortunately can be used to hide the sins of a previous repair. Hopefully that retro wiring mess is only on the coolant sensor.

Air flow meter, or mad sensor. Maybe!

I got suspicious in the beginning with throttle Position sensor wiring and the map sensor Hose but sure enough you were persistent And that’s what it takes with a jaguar V12 especially a Mirrelli ignition car. I have a 1990 Xjs rouge edition It’s been sitting picked up over The winter going get it running this Summer.

I gave my wife a scare when I yelled "hooray!" the moment the car started 😂

THE….. BEAST

Hello, Mr. Adam, I have a third-generation xj12 car. The car does not respond when pressing the accelerator pedal. After I disconnected the vacuum, the car started responding normally, knowing that I replaced the fuel regulator and the pump. What is my problem? Please reply, thank you.

‘you into bankruptcy.’ I finished your title. You’re welcome.

A V12 should start relatively instantly. Cranking it over continuously is only wearing out the starter and ring gear. Just my 2 cents worth. But congrats on finally solving the problem.

Only jaguar would put the engine in the front, ecu in the boot ( trunk ) then ask Lucas to wire the two together !!!

Injectors to not open "on time", rather the number of injections and time it stays open changes. Where the pistons/valves are is irrelevant for the injection system, only RPM/TPS/Temp/MAF matters.

Should change the oil at once!

Best we do in NZ is get rid of the V12 and put a 350cui Chev V8 in it problem solved

New airfilter. Probably mice nest.

That's why they make kits to put Chevy V8 engines in Jaguars

or 4😂

the reason jags have so many problems are the 'mechanics'.

3 minutes 😂😂😂

Stop cranking it for so long, you will burn the starter motor out.

What a terrible re wiring job ! Good job of trouble shooting.

I am sorry I have followed your channel for years but that intro with that bloody awful noise (yes it was an engine, but come on you are better than that) it was REALLY annoying, please get back to normal

Hi Man, Love this movie, what amazing, i am making notes of every step. BTW see your Instagram inbox, and send you a DM! :)