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Hi all! I just joined the jaaaaag club by proudly acquiring a stunning pack of trouble. A beautiful XJ 12 vanden plas 1990 with only 71 000km ( very good shape ). The car was sold to me at a good discount because a problem: the car would not fire the B bank ( driver side ). The exhaust smells like gas though. Upon researching it, I found that the ignition had this problem of having one bank fail due to half of the distributor failing due to a badly made italian cap ( marelli ) installed on 5.3's upwards of 88. I bought the car laughing because I though it was an easy fix. Aaaaand here's the surprise: I have a 1990 XJ with the Lucas vacuum advance... wth? It must be authentic because the hood has a decal mentioning the vacuum advance.
It gets better: In the papers, I found a service note mentioning rough idle and misfire from jag dealership at 20 000km dated in 1994 ( they said faulty spark plug wires and wrong routing, but it's just a technical bulletin, no repair mentioned ).
The previous owner seems to have tried new wires and maybe a distributor cap ( I'm unsure about the later ) and his idiot mechanic decided that it's a blocked catalyzer and emptied it.
I'd love to check the sparks, but I can't figure out the relays to unplug the gas pump to avoid having the whole place smell like gas. The internet is surprisingly short on technical data on these cars and I'm still hunting for a complete shop manual. The most puzzling thing is how come I have vacuum advance when it's a 1990? It's unlikely that the engine has been replaced or modified unless they bothered to put the vacuum advance sticker on the hood. Do you know where I can find technical data on the engine and the relay diagrams ( I tried google... almost nothing ).
Besides that... tips on best cigars and golf courses I guess...
Welcome to the Jaguar Forums! It's great to have you with us.
If I recall correctly, your car falls into one of Jaguar's transitional periods, when the 6-cylinder sedans/saloons were the newer XJ40 body style and electricals, but the 12-cylinder sedans were the older (and beautiful) Series III body with the earlier electricals and ignition.
The XJ40 looks like this, with no curvature in the bodywork around the headlamps:
The Series III XJ12 looks like this:
If your car looks like the lower photo, repost your questions in the forum for the XJ6 & XJ12 Series I, II and III, where you'll find more knowledgeable owners of similar cars.
There are a lot of documents available online, including Electrical Guides and other service documents. The full Jaguar Workshop Manuals are available on DVD from the Jaguar Daimler Heritage Trust (jaguarheritage.com).
Check the free downloads available from this forum:
And also check the downloads available at the site below, which is run by our forum member Gus. You will sometimes find documents for different model years filed in the wrong sections, so if you don't see it in the section for your car, try the next earlier or next later section:
I'd love to check the sparks, but I can't figure out the relays to unplug the gas pump to avoid having the whole place smell like gas.
I can't remember which is the fuel pump relay...but you can always just unplug the connector at the pump itself. It's just aft of the spare tire
The internet is surprisingly short on technical data on these cars and I'm still hunting for a complete shop manual. The most puzzling thing is how come I have vacuum advance when it's a 1990? It's unlikely that the engine has been replaced or modified unless they bothered to put the vacuum advance sticker on the hood. Do you know where I can find technical data on the engine and the relay diagrams ( I tried google... almost nothing ).
You don't have Marelli ignition because Jaguar didn't use Marelli on the Series III V12s.
Tech data is indeed very hard to find on these cars as they were rather low production. However, the info found in manuals for the pre-Marelli XJS V12s is generally close enough to be usable and helpful....with respect to ignition and fuel injection.
12-19-2015, 12:06 AM
XJ12 1990 B bank failure
