Back after almost 2 years. I sent out the AAV valve to have it rebuilt. I installed the rebuilt valve and called it good for the time being. Never ran it long enough to check surging problem. It ran excellent for the short time I had it running to put it into storage for the winter and moved on to other projects. Out of storage and back to my garage to repair oil leaking onto exhaust manifold. Valve train cover gaskets and half moon rubber gaskets and bought new parts where needed. The valve at the air manifold was inoperable. I bought a new one and replaced it. I repaired the air injection manifold and connecting parts. Most of the air injection holes in the head were plugged shut. I reopened them and reinstalled air header with new seals, trying to keep everything as original as possible. (mistake?)
I replaced all cooling hoses and vacumn lines that I could.
Now the car will only start and run for a short period of time. When I try restarting it fires but wonât run on its own. When I stop cranking it runs on for a couple of seconds and stops. I thought maybe fuel problem, I installed new filter and I ran fuel past injectors into a clear jar, clean fuel no debris whatsoever. Fuel pressure is at 38.( I left my pressure gauge in fuel line).
I rebuilt throttle linkage bushings and set throttle butterflies to spec, linkage bushings were very sloppy, well worn. I noticed throttle sticks at full open now. It didn do that before. I didnt change length of rods at all. Return springs aren`t enough to return to idle so I reset stop screw for now to keep from wide open by mistake.
Any vacumn connections on the right side of motor were sketchy at best. All the pictures I took help considerably but I still had to guess on some. Is there a single connection I may have missed that can cause all this grief? Or a reversed wire somewhere, my wires at the top backside are hard to identify. Would throttle position switches cause this no start condition? Would the air pump connections cause this connection. I could not find any decent schematics for this side of engine.
Thank you all in advance and Kirbert for your last bit of advice 2 years ago.
Unfortunately, Kirby is not on our forum anymore.
You did quite a lot. One thing you didnât note replacing, was the GM ignition module? $40 part and super important for the Lucas ignition V12s. A bad one will not operate when hot.
Yep, replaced that too,a little over 2 years ago, injectors are all new, redid the harness, it ran great, except for the oil on the manifold. This problem of not starting properly happened just since I changed gaskets. Thats what has me baffled, again! Im thinking maybe a wire is reversed or hoses from the air pump, vacumn lines. Im just getting back to it again so when I make progress, I`ll post it. Thanks again.
Iâve been away for a while myself. When did this happen? I hope it wasnât for health reasons
Long story shortâŚlast year he got temporarily banned for something he said (I have no idea what).
When he was allowed to come back, he chose not to. Our loss.
Yeah, like you said, itâs unfortunate. Good, bad, or indifferent, an icon (at least) in this community for sure. I wish Kibert well.
What ignition module did you buy two years ago?
It has been noted on the forum, aftermarket modules cannot take the heat of our V12s, and donât last long.
A genuine GM Delco is all to be trusted. $40 vs $20 for aftermarket.
Yea it was an ac delco. $70 at my local dealer
Ignition switch or wire?
Supposae that the circuit to the coil from the switch is OK and the engine fires.
but, when he key is released, and the circuit to the coil from te switch is now oen, the engioe, will stop.
So, test the circuit/
or, jump battery to te coil+. Crank as ususal. if fhe ennes continues to run woth the key in run position, you have verified the fault. the switch itself, the plug i behind it or the wire to the ci.
Good luck with the electrickeryâŚ
CHJ
Sounds like a fuel issue to me.
Bypass the fuel relay and see if it makes a difference.
Thanks for all the replies. I`ll post when I get it straightened out. I need to get a decent vacuum line layout.
Check the small 90 degree hose that comes off the AAV. It may be weak and the vacuum is strong enough to collapse the hose when the idle surges. Then when the idle drops the hose will return to its normal size and so on and so on. This causes the idle to ramp up and down. It occurred on my XJ-S. BTW, my AAV was bad too.
Thanks I`ll be sure to check it.
Mine has the layout on a plate attached to the right underside of the bonnet/hood. I have three labels/stickers on that side of the hood with the diagrams. There is another plate on left underside of the hood with the emissions layout.
If you have the stickers still there but are not legible, yet you can either make out the general drawing or especially the sticker part number, you may be able to order new stickers from jagstickers.com in UK. They had all but one of the stickers I was/am looking for (so I can install new stickers after cleaning everything and respraying the car).
Anyone have another source for stickers for the XJS?
Yes. The Coventry Foundation store on the US ebay site has s bunch of NOS underhood stickers. I bought several for my 87 XJS.
Jon
Thank you, I will check with them as I donât recall having done so.
Would you go more into detail about the GM module 40âŚwhere is it located, do I have one in my 89 XJS, and what does it control?
Thanks.
The GM/AC Delco ignition module was used extensively on many cars in the 70s/80s to take the place of distributor points. For our Lucas V12s (81-88) i believe it is used. For Marelli cars (89-) i donât think it was used?
Aristides,
Thanks for these vacumn line routing diagrams. I have one vacumn port I`m not sure where it goes. It is a 3/8" vacumn fitting under the right side manifold that went to the back of my air cleaner panel through a small metal gas filter looking fitting with 2 wires stating 12 volts connected and a directional arrow from air filter to the 3/8" vacumn line. This right side has always been a blur to me
I still cant find connections off of the air pump. The 3 way divert? valve was not connected to the air pump when I got the car but I did get the car running without it. I am going to bypass the fuel regulator as suggested, Fuel was my first thought also thats why I checked fuel quality and pressure and changed the filter. I have an inline fuel gauge that pumps to 36 lbs and holds. I have it installed just after the first regulator inline. Thanks for your help and when I get it straightened out Ill post results.