I am trying to check things off the list and am coming up a little empty.

'89 V12

The starter cranks but no start. I have spark at the plugs, I can hear injectors clicking and fuel pressure downstream of the filter is at about 42 psi dropping to 38 when pump not running and doesn't drop off immediately (down to about 30 after 10 minutes or so). When I pulled the plug it was sooty but I have no indication it is firing off rich right now. I saw the coolant temp sensor can cause issues but can't find exactly what the resistance should be. If it is off is that enough to produce a no start condition? I don't know pressure at the rail as I didn't want to commit to cutting into the line to the outlet regulator. I will also say while cranking the gauge doesn't register any oil pressure build up but that may not be relevant. What else should I be looking for here?

Thanks!

 

Hi

Is your Car a Lucas or a Marelli?

Alex

 

It's Lucas ignition.

 

CTS resistance

5.90 kohms at 32ºF
1.18 kohms at 105ºF
0.60 kohms at 140ºF
0.32 kohms at 176ºF

Out of spec can over fuel the engine. Open circuit will swamp the engine almost instantly

Cheers
DD

 

Adding to Dougs replay.

Assuming you are in the USA, might pay to add that to your Sig, as these beasts do vary market to market.

The HE WILL NOT fire with sooty spark plugs. They will also NOT burn clean a sooty odd one or 2.

Replace the plugs, gapped to 0.025", and dont forget to CLEAN the "V" before removing any sparker, and apply a smear of Anti-Seize to the threads of the newbies.

Read my sticky at the top "No start of a HE.........". lots in there.

 

Thanks Grant, I fixed my signature and will start pulling plugs!

 

Before you start swapping plugs, put a new one on a lead and see if there's spark. If they're fouled they need to be changed anyway, but its not the only thing that could cause a problem. If you have spark, great. If not, check out the white wire of doom. It will cause a crank no spark condition on Lucas cars.

 

AND

By spark we are referring to a FAT BLUE CRACKER of a spark. Anything else is useless.

OH

And fill the beer fridge, ya gonna need it, ha.

 

Worth doing this too as a preventative, though it might be a factor too:
https://www.jaguarforums.com/forum/x...sistor-134745/

 

Thought I would give an update.

I wanted to confirm fuel supply so did the following.
- ran the pump supply straight into a separate tank in case crud in the tank/sump was blocking volume. No change in start.
- disconnected 1A injector to check the clicking was actually injectors firing. It both fires when pressing pedal to the floor with ignition on and pulses while starting.
- I also went ahead and replaced the CTS with no effect.

From this I am pretty confident there should be enough fuel supply to at least have it fire if reluctantly so I am going to focus on the spark. As I said before, it does have spark but I don't know how healthy it is and haven't confirmed its timing. The car only cranks at 500-800RPM according to the tach no matter how charged the battery or even jump starting the car and once I did have to jiggle the ignition switch to get the starter to fire so there is a loose connection there but I should think that wouldn't affect voltage to starter. I think I will be cleaning/changing plugs and checking cap/rotor. The timing is electronic correct so it shouldn't be an issue (there isn't the distributor having been pulled issue?) *Note I have never seen this motor run only heard from PO that it had run off with fuel poured in from return line fitting.

 

If it’s a Lucas car then the timing is mechanical/vacuum, not electronic. You have one big round distributor right? I ask because ‘89 was the changeover year, and a MY89 car is probably Marelli.

Assuming it is a Lucas car, the timing probably won’t be so far out that it won’t run. The advantage of having so many cylinders is that there’s a lot of overlap. But check that the leads are routed correctly.

On my car, the tach doesn’t register anything until after the engine is running.

 

More reading for you above.

HE tune up spells it out simply.

NO the timing is mechanical, and unless Freddy has fiddled with it, will not move. Even if the timing is "out", the beast should cough and fart, and even run.

HT leads, ALL 13 of them, should be replaced. They have about a 5 year life in the V12 engine bay.

Spark quality is the key.

Crank speed, about right, move on McDuff.

Remember, just because an Injector :clicks: does NOT mean its passing fuel.

Do the spark thing first AT THE SPARK PLUG, and then suspect fuel later.

 

Update- New plugs and coil, cleaned grounds jumped CTS. Still no change. There is a bit of a voltage drop at the + coil while starting so I was trying to address that. I ran a jumper from the firewall bus to the coil and no change. I am pretty stumped. Any way something on the amplifier end is causing the weak spark? Still need to check spark quality at the coil lead so it could be cap/rotor or maybe PO has really messed timing up after pulling the distributor. Getting real close to heading to the scrap yard.

 

Given all the checks you have made to date on both ignition and fuel, I would be reluctant to junk it unless you have carefully acted upon the guts of Grant's latest post (#12) . . .

Yeah, my added emphasis, but to remind me of my "no start" despite following all found here many years ago. As quoted here and also in Grant's Sticky, this gem pointed to my solution . . . admittedly an older '80 V12 XJ-S. Fuel pressure at rail, but my "clicking" injectors were so gummed up, they did NOT actually squirt fuel when tested out of engine. All but 3 came good with pro cleaning. Those 3 were were replaced with new. Refitted, engine sprang to life!

Somewhat rough at idle, but running nicely.
New full set of HT leads to go with new plugs and rejuvenated injectors . . . solved!
IMHO, it's well worth pro shop testing, cleaning or replacing.
Cheers,

 

I pulled an injector to watch it while starting and at least that one was squirting fuel. I should at least have some sputtering if there is a good spark.

 

Yes. The amplifier could have failed, or the white coaxial cable that carries the signal to the ecu. There are threads on redoing both on here. Neither are difficult, and both can result in weak or no spark.

Do you have any spark at all?

 

Yes there is spark but definitely not a hot blue one.
Edit- I was able to get a plug on the coil to distributor wire and the spark looks good there so on to wires/cap/rotor. Just no way around replacing these service items!

 

Geting there.

Spark, healthy, at the cap FROM the coil, eliminates shiiit loads of stuff.

Inside the cap, there is a carbon brush that passes that current TO the rotor for distribution. THEY WEAR OUT, THEY FALL OUT. The damn thing wills start, eventually, and run well for about an hour, then that cap post inside the cap melts,and brown stuff hits the fan again.

That coax mentioned is ONLY to tell the ECU that there is Ign Pulse, so wake up the Injectors, pllease. You have injector activity at crank, so move on from that one.

Inside that Amp , in the corner, is a Condensor looking thing. If you are old enough to remember Contact Points Ignition Systems, you will recognise it quickly, Remove it, give it to dog as a toy. They are not needed these days, and age has them "leaking" to earth, thus messing with the Amp and spark quality.

Timing, Nah, that has zero to do with spark. Its only purpose is to deliver said spark to the cylinder at the required time.

Grab a spark plug, plug it into one of the leads, and lay it on the engine area, Inlet bolts, head dome nuts, carnk the thing, and see the quality of the spark. DO NOT remove any of the 12 to do this. Coz if the thing starts, you will be fighting a serious fire.

 

Do you happen to have a part number on that brush and spring?

I saw somewhere there can be a situation where the injectors stop after the engine starts. I have noticed pumping the accelerator while starting seems to cause it to want to start a bit more so than no accelerator.

 

OK,

I go WAAAY back, that brush and spring WAS a GM part down here, 9417????, I forget now, and we used them on all sorts of cars, not just Jags, 6 and 12.
Looong time NLA, sadly, but coil over made those things redundant real quick.

That Injector pulse, YES.

There is a wire that runs from the Starter Relay TO the ECU, to jump start the Injectors during cranking, THEN, that Coax wire takes over and supplies an Ign Pulse to pin #18, and the Injectors keep injecting. That coax is a failure item very high on the NO start list.

Pumping the pedal, triggers "squirt" fuel, like an accel pump in a carby, and thats all.

You may have a TPS too far out of range, 0.32 t0 0.36 at idle position is required.