New to this forum. After much helpful information and insight from another forum I thought I would use this site also. My problem is after much cleaning of my project and not knowing if it even ran I got it to the point of turning over. After much testing and deliberating over the various problems I encountered, broken wires, bad grounds etc. I got it to the point where it started. The next day I went to the garage proud of my accomplishment I was going to get it off the wheel carts, change oil and more, turned the car over and now no start situation. It hasn`t started since then. I have an in-line gauge for monitoring fuel pressure 38lbs while cranking and falls and holds at 30 when I stop cranking. I have checked spark at coil , good spark. I checked spark at a single plug 3b and it sparks at this plug. I have new fuel injectors in and I pulled the 2 front ones out to check the stream and it looks good at both injectors. I tested the windings of each injector and all were good with consistant readings. I test all injectors with a test light and I have 12volts at each injector grounding each one to the block. I rigged a light to test the injectors through the connector and at each injector the bulb lit. What confuses me is that when I tested each injector with a volt meter through the connector the B bank tests 12 volts at each injector. when I checked A bank the voltages were all very erratic and moving so fast I couldn`t even get a reliable reading on any of the injectors. I picked up two ECU`s 6cu`s from local junk yard and neither worked to start the car, but both came from high mileage trashed cars so I was very skeptical that they would work. Mine is a 16cu. I just ordered a 16cu off the internet hoping this one will get me started. I will post when I get it in. Coils test good, new spark amplifier, new coolant sensor. new cap and plugs and of course a new fuel filter. I cleaned the sump and to be sure I caught some in a clear jar and the fuel looked good. The number 3b plug is pulled and grounded so I can monitor the spark and there is a spark every time I turn it over. The injectors are what is puzzling me.. does any one see anything that I am overlooking or is it the ECU that I`m hoping gets me started again. Any insight will be greatly appreciated. Rod By the way when I did have It running for the first time it seemed to run well ,it revved good, I turned it off and it restarted as I believe it should, I turned it off and quit for the day on a good note. Thanks again

 

Start here:

https://www.jaguarforums.com/forum/x...he-v12-178286/

 

Are the plugs wet with fuel after when you turn over the car on the starter?

there is one item you do not mention this one: Worth cleaning etc.
https://www.jaguarforums.com/forum/x...sistor-134745/

Will the car try to start on ether (ie those cans of quick start stuff)?

Basics are called for here:
Wet plugs = fuel is getting in.
No popping or banging, if fuel getting in must = no spark.
No starting or trying-to start on ether = no spark/not good enough spark - whatever it looks like on testing.

A clear identification of fuel or spark being the problem is the first thing to get to.

Are the plugs and HT leads and Dizzy cap and rotor new? Is the carbon brush in the dizzy cap centre?
Is the white wire from amplifier to ECU being earthed by mistake (eg broken insulaton?).

 

I have read your scribe 5 times since 11AM, and its now 6PM, and many thoughts, and beers have crossed paths.

With Greg 100%.

Spark, OK, you got spark AT the plug, BUT, is a BLUE CRACKER of a spark, or a washed out excuse.
Your market has the 11.5:1 comp engine, the lower spec unit, and if that spark is NOT a good FAT BLUE CRACKER, it will not run. You could coax it to run eventually with the washed out version, but that would be a lousy running V12 st best.

The erratic readings of those Injectors, points me straight to EFI loom failure. Age, rodents, the fact you found broken crappy wires already, just adds to that observation.

Engine Earth strap fiasco, simply attach a dedicated Earth cable (good thick one) from the engine to the chassis, tidy it up after the beast runs. A Battery Jumper cable will do.

The wiring INSIDE the plug and rubber boot, of the CTS (Coolant Temp Sensor), located on the aft section of the B bank thermostat, is 98% of NO start V12's. Unplug that unit, pull back the boot, look very carefully, and repair if needed. If you are 100% OK with that plug/wiring, then use a paper clip, bridge the 2 terminals IN the plug, and try again. That bridge informs the ECU that the engine is "at operating temp", so its good to go.

The FANTASTIC Coax cable (AKA dreaded shielded wire), that transmits an Ignition pulse from the Ign Amp TO pin #18 of the ECU, NEEDS to be checked for Integrity. NO pulse received, NO start the V12, its that simple.

Read my sticky at the top "No start.........."

OH, and Welcome to the Forums.

When the dust settles, please do an Intro in the New Members Area.

 

I'm going to court controversy here and state that many make a huge mistake when waking these cars from a prolonged sleep. Whilst you did the right thing at the fuel tank end you make no mention of any actions at the engine end, fuel that looks good isn't an appropriate indicator, dump it - ALL of it. Based on my experience with a car that slept for 18 years if you don't clean out the injectors and ALL fuel lines before you start messing about then you are stacking up problems for the future and simply putting off the inevitable, wasting time on systems that are in an unknown condition, running a V12 lean (insufficient fuel) is not going to end well. Despite new fuel pump and fuel filter etc my fuel lines and the rail that supplies the injectors were full of 'stuff' - corrosion too - so when started that simply filled the filter baskets of the injectors - a number of them were totally choked - note you said it started but now won't. I know when we get a new toy the temptation to get the engine going is super high but it is premature enthusiasm, I made precisely this mistake, it proved the engine was OK but nothing more. Now you have seen the engine is 'good' the absolute first step should be to completely gut the fuel system, followed by the underbonnet electric, every cable and connector needs attention (in my opinion) - you will need to do it eventually anyway on any Jag that has been laid up - it isn't a case of may do this particular job - its a mandatory task unless you fancy a barbeque at the side of the road one day - fuel under pressure is not to be underestimated and old electrics can cause major head scratching sessions at the most inconvenient times. One issue my car had was a broken wire on the sensor feed in the distributor - sombody prior had repaired this - BADLY


How not to repair hard to get at cables located in hostile environments.


You say that you have an inline pressure monitoring point - where - there is only one place to accurately measure a HE and that is after the first regulator and before the fuel rail - their aint much space there - pressure from the pump is irrelevant - it is pressure in the rail that matters.

Grant's sticky - not start of a V12 is the second thing to do if you're confident that the engines good, Grant's sticky on Post purchase is absolutely number one >> Post Purchase Worksheet

I think that the list on page 4 needs amending to add a 10th item - a friendly bank or deep pockets and a wife that realises you need psychiatric help (or no spouse at all) are all things that should be on this list - with a Jaguar this old you gotta pay to play I'm afraid.

Not withstanding everything else can you get a click out of the injectors, to Grant's point - erratic - hmm. Follow the guidance in this vid to check you can get a click on each injector .... >> the bit that may interest starts @ 11:39

You should be able to hear clicks when somebody else tries to start also - and even by rapidly advancing the throttle. A cable connected doesn't necessarily mean there's a good circuit.

If you have spark and fuel then there should be no reason for not starting - but you must have both in good order. Just to support previous remarks the spark needs to be 110% - a spark in the open air proves nothing - spark plug function is inhibited under pressure, the higher the compression the better the spark generation needs to be - higher voltages etc etc. This relies on both the plug condition and good circuits, resistance anywhere is going to steal energy from the spark, that includes plug leads / earths etc - don't be so sure spark isn't leaking out of the plug leads (try truning it over in the dark), the spark will find the easiest way to ground which isn't always where you think. Don't get carried away with cranking too - if you cook the starter I guarantee you won't be happy - they're big, heavy and an absolute mare to replace.

 

Thanks for the responses. I`m going to answer what I can remember was asked. The CTS was replaced and I did test the connection to the ECU and it was good, I also short circuited the wiring with a paperclip before the new CTS, no start. The pressure gauge in the fuel line is inline after the first regulator and before the fuel rail. 38 lbs while cranking and 30lbs hold. Spark amplifier is a new delco. I didn`t change the condenser figuring it was more for radio noise than starting /running problem. I cleaned the resistor pack terminals and took it apart to see what I could see and all looked good. The tank was drained and new fuel added. I haven't tested for wet plugs but I did pull the fuel rail with injectors installed and cleaned them with my ultrasonic cleaner. These are a new set of injectors and I figured it wouldn't hurt. While cleaning I fired the individual injectors one at a time while blowing through them and I got bubbles at each injector as I tested them so they opened and were unobstructed. I still have the dual coil system on the car. I bought a new coil and installed it alone and had I weaker spark although it tested ok so I put the original coil back in with a secondary coil and I had a better spark so I left it for now. The car did run with the single coil though. My testing is spot checking and I realize this isn`t optimal but short of taking all injectors and plugs out and starting from scratch with my testing but I thought that it did run and ran well and then not starting and running these procedures would do for now. I will dig deeper if and when I have to (again). No one really addressed my fuel injector differential between my A and B banks. Shouldn't my A bank and B bank test equally with the same results? As I said I tested all injector wiring with test light grounded to the engine block so each one lit. I tested with a home made setup with a bulb through the connector and each pulsed when I cranked the engine lighting the light but when I tested with volt meter the A bank tested with erratic and wildly flucuating readings. I actually couldn't even get any kind of a recordable reading but the B bank registered 12V and steady readings. The car doesn't even try to start, not a hiccup or fart. No fire after having it run that one time for 10-15 minutes. I had it running one time before that but it ran terrible smoke and misfire so I pulled the cap and cranked the engine so the rotor pointed 180 from previous position. That is when the car started and ran, then not. As I said I have a spark, I have fuel, and I have injectors firing in order or not. My new to me ECU will be in next week and if that works I'll be pleased, if not back to basics. Maybe a timing chain jump ( not ready to go there yet though). Most of these tests were recent but many have also been done over the last 3 years so it has been tested and retested and this year was the first that it ran for any length of time. One other thing, there is gas in the crankcase so I thought that indicated the injectors releasing fuel but not necessarily when it should be released. The oil will be changed as soon as I get it running again. Thanks for all the help and suggestions and I seriously consider each one. None are dismissed. Thanks Rod

 

In his reply, Grant Francis mentioned that he thought the flucutating injector pulse voltages indicated a failing/shorting injector loom. This will cause fuel in the crankcase sump oil in large quantity, AND no-start through flooding. An earthing injector loom holds the injectors permanently open. I would renew this immediately or build yourself one.
I very much doubt the ECU is your problem.

 

Ben
Where did you get those lovely inlet blanking plates from, as shown in your photo?

 

Hi Greg - I designed in Fusion 360 and printed them.

On the original thread .. I'd replace the condenser but you can check it if you have a decent meter (kind of) - it is essentially a capacitor and can be a weak link depending how old - old capacitors have a tendency to become resistors, for what they cost replace it - you should be able to charge it with a multimeter on a high resistance range - if it doesn't charge or is shorted it is a bin job.

I concur with Greg / Intermittent 12V is a concern - should be constant it is the ground circuit that is closed by the ECU as required via the power resistors - you might want to check this voltage at the place where the injector harness is connected near the right hand headlight. You could try putting 12V to the appropriate connector. I don't know if you have a multimeter but you need one. If each one lit with a bulb between !2V and the engine block I'm not so sure about the eratic reading part - note the injectors have 12V at all times the ignition is on - it is the ground that is switched and if you hold the coils energised for too long you will be buying even more injectors.

You need to be careful with coils too - there are two types of canister coil - one is designed to have a full 12V directly, the other needs to have a resistor in circuit, I am actually not sure which type the Jaguar is - I think it is the former. If you don't have the service / repair manual for the HE then it is time to acquire it, there is a lot of debug / diagnosis information in there precisely for this kind of thing - not trying to be flippant here but it is very hard to diagnose things like this at a distance.

There should not be a difference between A and B banks - even so you should have some signs of life. Don't go complicated until you eradicate the simple, don't get rabbit holed on the 'I tested that and it is OK' - that's caught me out more than once. Timing chain jump - remember the not complex rule - this shouldn't be an issue unless the engine has been rotated counter clockwise in which case the tensioner is probably toast - but not withstanding step one is to get A and B bank injectors the same voltage wise, don't be so convinced that a spark in air means you get one in the cylinder - we used to test spark plugs by subjecting them to pressure (had a special bench tool specifically for this). The V12 is very sensitive to any deficiency in the ignition side - even down to the plug gaps - 0.025". Consider that ou disturbed the cap and the car then started ... not sure what the 180° is all about - have you had the distributor out ? ...

 

I`m in personal repair mode after a 5 month Covid delay of my daughters wedding reception (last daughter of 4) one son left. I`m feeling much better now and I did manage to get to my project for one quick test, I turned the key on and listened for clicking sound when I turned throttle capstan. I could hear it clearly.
I would consider the spark as strong anything I have worked on, usually on points and carbourated car projects and drivers alike (tractors, bikes,4 wheelers etc. also) This is the first fuel injected system I have ever tried to trouble shoot and it is definetly a learning experience.
I made a mistake in explaining my testing procedure. I tested all injectors on A and B banks individually with a 12 volt test light grounded to the engine block. They all lit the test light when touching the appropiate terminal when I turned the key on. Both A and B banks. I made the same test with a multi meter using the same method and again ground to the engine block. They all tested at 11.5 volts with my multi meter.
I also tested with my homemade test light that I made with a dome light bulb wired to a connector that fit the fuel injector harness plug at each injector alone, each one pulsed lighting the test light when I cranked the motor
My next test is the one that confused me the most and I was mistaken with the voltage reading. Again I tested each injector wiring harness one at a time with my multimeter and the B bank all tested with a lower voltage, if I remember correctly the reading were 3 or 4 volts which my manual said they should read and all reflected the same readings. I previously stated they all read 12 volts which was not the correct reading.
The A bank is where the wildly fluctuating readings were taking place. They were fluctuating so fast that I actually couldn`t get a reading, but they were each fluctuating the same if that makes any sense. Nothing at all like the B bank readings, not even close.
Moving the rotor 180 degrees took me from firing on the opposing tower on the cap tower to the proper one. I either turned the motor over when I had the cap off or it was that way when I got it and when I first put the new cap on I followed the position that was previously on it. That is when it started and ran well, then not the next day. The previous owner told me it ran when he parked it, I`m not so sure now after finding an oxygen sensor loosened and disconnected, the EGR valve disconnected not to mention a few other things.
I took the ECU apart to see what I could see and I found a suspicious looking glob of solder where someone had tried some sort of repair. I`ll post a picture of it when I can. I traced it the best I could and it went to the resistor pack A bank. This is why I went looking for another ECU. This was another of my suspicions. I heated it with my micro torch and resoldered the bad spot but it made no difference in starting. I may be wrong but its my best guess for now.
I visually checked the fuel injector wiring harness when I had it apart and found nothing suspicious but I will check the harness connector at the resistor plug, I didn`t think of that, good idea. That would tell me what kind of voltage I`m getting from the ECU if I`m thinking correctly. I did smell a very faint electrical smell coming from the valley area that I couldn`t pinpoint. Maybe something fried while I had it running. I shut it off and ended on a good note when it ran, maybe it finished burning off when I shut it down. I`ll post when and if I find out what the problem is. Thanks for the input

 

Its early and I will read this again later, adding any new thoughts.

That condensor inside the Ign Amp is not needed, so remove it.

The Injectors get a 12V Ign signal to one terminal, and the earth is achieved via the ECU. So you should have 12V +/- on one terminal of each Injector, unplugged from the Injector.

The 2nd terminal should then be tested for "leakage" to earth, again, unplugged from the Injector.

If its got spark., and bang juice inside the combustion chamber, it should fart, as you say But with fuel IN the oil, she be flooded, so, you have a loom opened to earth, and all the other tests are simply not picking it up.

Timing chain, NAH, maybe at 800,000 kms, but I seriously doubt it. Chain tensioner (Boomerang), YES, but the engines still run just fine. Done a few of them over the years. Silly people rotate that engine "backwards" and snap the pivot. NOT causing your issues.

I will keep thinking. These are SIMPLE systems, only made complicated by over thinking. FACT.

 

Right, the pretend Jag is sorted and running as it should, at last.

My suggestion now reading this whole scribe 3 more times.

Unplug ALL the Injectors. Spray some Ether up the Air Cleaner snout, a GOOD spray, as its got to get past the filter. Go for start,. If it starts, coughs, farts, then the overfueling we are discussing via the Injector loom is the root issue I reckon.

The air filters may prevent Ether getting into the system, so look at the vac spigots on the throttle bodies, and spray through there.

DO NOT try and start a hard to start V12 without air filters installed. They have a BAD habit of belching flames out the throttle bodies, NOT good for underwear or the paint on the shocker towers.

I doubt you have Cold Start Injectors, but I cannot see from here. If you do, unplug them, they will flood that engine in less than a heartbeat. I remove them, and plate the holes, on any V12 that darkens my door, they will drive you to drink, fair dinkum.

If it still has no bang for the buck, its losing spark from compression pressure, so coils, leads, etc etc are giving grief.

 

My ECU is a 16CU. I tried to upload a picture or 2 of the solder job but couldn`t do it for some reason. I traced the circuit back to the resistor. I did try to resolder the bad joint with no difference in starting situation. I do have cats and o2 sensors and I have an 16cu ECU coming from California any day now but I am going to rebuild the harness because of todays test.
I checked the continuity in the wiring to the injectors as BenKenobi steered me in that direction The way I tested today. I unplugged the harness wiring from connector in the wiring just before the resistor with my multi testers audio output (beeping) I checked A1,A3, and A5, A bank A2,A4 and,A6 All wiring to these cylinders had continuity ,no crossed or shorted wiring . So to me A bank checks out being okay. I was thinking A bank was not right originally. It had fluctuating and eradict reading but I`m thinking now they were working as they were meant to work and the B bank is the culprit with the steady readings. I tested B bank B1,B3 and B5 tested as they should with continuity but when I tested B2 and B4 both connectors each lit from 2 different pins at the other end of the harness yet B6 tested ok. So something on the B2 and B4 injector wiring is crossed up or shorted. I don`t know what it means but it isn`t right. I don`t believe this is enough to keep it from running but I`m sure it will run better when I do get it started. Thanks for pointing me to another way of testing the injector wiring .The other 3 tests didn`t turn this fault up because each were tested individualy and if I would have tested in groups of three any of the other 3 ways I would have caught this fault in the wiring. Thanks again.

 

I decided I`ll rebuild my harness my self and save myself 2 or 3 hundred dollars. I checked on new and even some used harnesses and ordered the high temp 6 wire color and connectors from the internet .The connectors came today and with a bit of rework they will work fine. I have to trim a little plastic off the back of the connector because it interfered with the fuel injector mounting plate but it fits nicely and tight once connected. I`ll take some before,during and after pictures. Thanks for the interest. Rod