Problem:
Vehicle starts after a few cranking cycles. Idles around 600 rpm. After about 30 sec, idle jumps to around 1000 rpm for about 5 sec, then completely dies. Vehicle will start again after a few minutes of cranking cycles, but dies immidiately.

What I have done so far:
- fixed water pump leak
- new plugs (gapped to .025)
- new single coil (.62 ohm primary)
- cleaned injectors

Initially after replacing plugs and setting timing, it seemed to run ok, as I was able to hold 3000 rpm in order to set timing. After turning off and cleaning up around the garage, I had the same issues as before. I’m not sure if I have a fueling problem, electrical problem, vacuum, or timing? Anybody have this engine shut down after a seemingly normal idle before? Not sure where to go next.

 

How is your fuel sump tank and pickup filter. It may be a fuel starvation issue due to blocked filters.
If you can't vouch for filter renewal or sump tank clean out it's probably a good idea to do it anyway.

 

Firstly welcome to the Forums.

When time permits, please do an Intro in the New Members Area.

There is a "sticky" at the top that I wrote a while back, that covers many issues with these cars/engines.

Obviously some of it you have covered, some of it is not related, but maybe there is something there that could help.

Along with fuel supply, as already suggested, I reckon the AAV is hissy, the mechanical advance in the depths of the distributor are jammed, the multi pin plug and socket on the bottom of the EFI resistor pack needs a good clean, the TPS is out of range, or simply dying.

A very methodical and systematic approach is needed. Simply throwing things at it, and moving around system to system without a plan, will drive you nuts.

I have been intimate with these engines for far to long, and they are SIMPLE, but you need to follow a plan.

 

Baxtor:
I have not cleaned the sump or changed the filter yet. I should be able to eliminate those as a problem with a tee after the passenger side regulator to a pressure tester. Correct?

Grant Francis:
Thank you I will do that soon. I have been through most of the stickys and issues talked about on here and many many other forums. Though it seems the specific problems I am having with regards to how it is behaving is different than others. Most diagnostic advice I am finding requires a running engine, which mine isn’t (for longer than 30 sec anyway). I am trying to go about it as systematically as possible. My first problem to overcome was the leaking water pump. While reassembling the engine after changing plugs, I noticed the original capacitors were out of spec on the primary winding ohms, and the capacitors would get very hot. So that was my first replacement part.
i have checked the TPS upon reassembly, and it checked within spec and operated smoothly.
i sprayed the multi pin plug out with contact cleaner upon reinstall of the radiator.
I have not checked the AAV just yet. That will be my next check after the fuel pressure.

thank you

 

OK, the mud clears a tad.

Not running, oops.

The short period of running MAY be the fuel from the initial prime sequence, and the thing has no Injector pulse. this pulse is supplied by the dreaded shielded wire from the Ign Amp to Pin #18 of the fuel ECU in the boot.

I will dig out some Word Docos tomorrow and post for you.

 

OK, need these done now, sleep can wait.

These will help a tad I hope.

The pressure test is any "T" into a fuel supply line BEFORE the B Bank FPR.

This Drivers/Passengers, is going to confuse too many of us.

The A Bank is the RH side as sitting IN the car and facing the front. The B Bank is the LH side sitting in the same position.

Your passenger side is the A Bank, our passenger side is the B bank.

XJ-S ECU Pinout table.doc

Jaguar V12 HE RH fuel reg removal.pdf

 

Grant:
My mistake. I meant a tee after the A bank FPR. I assumed the fuel supply was good since my diagnostic of that and the injectors was as follows:
- Pulled entire fuel supply rail with injectors connected
- disconnected fuel return hose after B bank FPR and ran into a fuel can upon a jumper of the fuel pump relay (appeared to be good flow)
- reconnected return line and put jumper across fuel pump. Then i went to each injector individually and supplied 12V power to the injectors to check function (All seemed to have good pattern and pressure)
- disconnected fuel fill cap and blew compressed air through the fuel return line (appears to be free from obstruction)
It was upon re-connection of all this with fresh plugs that i received my longest run time of the engine (roughly 5 min). After that, it would produce the same problems as before? I will check the pressure after the A bank FPR first while it runs (for 30 sec) and see if the pressure drops upon the engine dying. If the pressure stays constant, and the engine dies, my search will move to injector pulse and then to spark and timing I am thinking.

 

Quite a few bases have already been covered.

Years ago...long enough ago that the details are fuzzy to me now....I couldn't keep my XJS V12 running at idle. Long story short, the left and right throttle blades were not equally adjusted. It would be OK for a few moments...then the engine would lope a bit...then the engine would die. Hard to restart. Sound a bit familiar?

In my case I think the mis-adjustment was a problem I created. I have a vague memory of that. My memory is much clearer on things I *didn't* bollix up, though

Anyhow.... throttle bores are often clogged. Cleaning them, setting the throttle blades to the proper .002" gap, and synchronizing the linkages is something that many old V12s need just on general principles.

No guarantees but it might be worth looking into?

Cheers
DD

 

Doug:
Yes that does sound familiar. I do have an issue with the RH side throttle assembly. It seems the bushing is destroyed/missing. I planned on making or buying a new one and resetting the throttle blades to .002. I have cleaned both throttle bodies however, and set the gap. But I'm guessing that probably does not matter if the bushings are out!

It doesn't necessarily lope however, Its more of an "engine shut off" and then "diesels" for a bit sometimes before completely dying.

When it did run for a few minutes, I could hold the throttle steady around 2,000 RPM, then all on its own without moving my foot, it would jump to around 3,200, then back. But if I try to let the engine do this at idle, it just dies. And upon restart after this "event", i will die immediately upon touching the throttle (slow or gunning it)

 

Update:
Performed fuel pressure test. Rail pressure while pump was on was roughly 37 psi. When running the psi held around 30 psi. Checked continuity of shielded wire to pin 18, all was good. Checked for internal short to braided wire, and there was no short.
Checked for injector “click” with key ON, at first I didn’t get a click. Wiggled the shielded wire, and could get a click when rotating the throttle capstan. I noticed the injectors don’t “click” unless I move the capstan quickly. If I go very slow to full throttle, they will not click.
I did not have a wet plug however after a quick cranking with no start?
Cleaned the resistor multi connector.
Good blue spark at plugs
Bypassed the CTS
Engine will start, but only run for a few seconds. (I will try to attach videos)
Probably go to AAV next?

not sure how to attach videos...

 

 

As l recall the need to move capstan fast is normal.
How are you running the pump for pressure test? If jumping it are you trying to start the car with it still jumped.
It almost as if pump may be running in crank position but then shutting off, maybe?

 

Baxtor
Pump for pressure test was run from cycling the key on and off about 5 cycles to get a consistent pressure on the guage. The one video shows the guage pressure with the engine running, roughly 30psi in the rail with engine running.

 

A few ideas if all else fails:
When it stops and will not restart, have you immediately checked for spark?
I assume it is a Lucas car? If so, have you R&R'd the distributor, and checked the starwheel gap and the wires from the pickup that emerge out of the dizzy and go to the amplifier on B bank intake manifold?
Have you tried a new (or known good) amplifier?
Have you tested the TPS?


I had a no-start problem, on and off for quite a time, and cleaning the resistor pack plug eliminated it. About a year later the amplifier when hissy giving exactly the same symptoms and a new one cured that.
I am not persuaded about the AAV being faulty, even if it was the car should start after a few throttle pushes to prime the system a bit, and you should be able to hold running it on the throttle - which is all the AAV does.
Greg

 

Likely not the root cause but l don't think 30psi is enough but more so you could eliminate pump circuit as cause by jumping it to run then try start.
Cycling the key won't prove pump operation in run position.

 

Greg:
I ran the car one time with a plug lead removed (plug still in) and used an old plug to check for spark. The car started when i did that and i watched spark get delivered all the way through, even while it was starting to die, there was still spark.
I have not done anything to the distributor. PO said that he replaced the cap, rotor, and wires (all of which look new). PO also stated that car ran fine until the day he heard the water pump blow its seal and start leaking antifreeze. He said the car did not get over temp, and he had the car parked ever since (roughly 1-1/2 years).
I did notice on the distributor while i was replacing plugs, that the eccentric advance mechanism did not work? So I set the 1A cylinder to TDC of compression and checked the position of the rotor. At TDC and with rotor pointing at 1A, the distributor had to be turned all the way (clockwise) in order to line it up. with this being the case, there is no more movement for advancement, and the eccentric advance is over the top of one of the stop tabs?
Appears I may have to remove and evaluate the distributor.

 

Baxtor:
I will try to jump the pump relay and start today. The 30 psi was the constant pressure while the engine was running (the drop from static pressure related to the injectors firing i assume) and the static pressure was around 36/37, you can see both in the video. It seemed a little low to me as well for the constant pressure while running, especially since in a no start situation, the plugs are not wet at all, just covered with black soot?

Grant Francis:
I have followed every "No Start" test outlined in the .pdf you sent a link to. The only discrepancy i see from what you specify is the fuel rail PSI and not having wet plugs. There were no steps or tests specified for the dry plug situation to try and resolve it? I know the injectors are providing fuel however because after pressurizing the rail, by turning the capstan with the key on, i can hear the injectors fire AND see the pressure gauge drop when they fire.

 

The dizzy sounds to me as though it has been replaced with the gear one tooth off. I think a good look at the dizzy is in order. The dizzy is driven by a spiral gear that meshes into the jackshaft that runs along the bottom of the V. As it is replaced, and the spiral gear engages the jackshaft, it turns the dizzy as it seats itself home, so when replacing it you have to allow for this.
I am not quite sure what you mean by the eccentric advance?
Also is it a Lucas car?

 

Greg:
Yes this is a Lucas car. The eccentric I am referring to is what i have circled in the pictures (not my distributor) and is outlined in Kirby Palms book on page 128

 

Yes, that is the timing adjuster, but if it is at the end of its adjustment range, and the rotor is only just at the 1A post, the dizzy is one tooth out.