Vacuum Schematic
 

Anyone happen to have a schematic of the vacuum line routing and connections pre-92???

I believe there is one in Kirby's manual, but you should have stickers under your hood as well.

EDIT, Deleted info and note to self: Pls engage brain before keyboard .,........

According to my info the basic system even for '94 onwards is still Delanair Mk III. Still four vac solenoids (same as before) So the Mk III vac diagrams "should" still be valid.

Per, looking for vacuum diagram for under the hood now on the 91 coupe. Just to make sure all the routing is correct. Looks like someone bypassed the charcoal canister and re-routed some lines, want to verify their locations and put things back like they are supposed to be.

Well there are two parts to the system on the '88 and earlier cars.

If you want to look at the vacuum advance for Lucas advance cars, here is a good treatise on it. You are probably looking at a "Emission A" system:

http://www.jagweb.com/aj6eng/vacuum.php

Here is a decent description and photos of what all those little parts are:

http://www.jag-lovers.org/xj-s/book/...omponents.html

For the other half of the system check out this page and click on the links to see vacuum routing diagrams for the various years. Look for the diagrams with the 'charcoal' and fuel pressure system.

http://jaguar.professional.org/vacuum/

Sounds like it is pretty common for the charcoal side of the system to be plumbed wrong, which will result in your fuel tank not venting properly. The rochester valve seems very finicky, so I just bypassed mine and vented straight to the canister. For the advance half of the system, I discovered my vacuum regulator was not connected properly, resulting in no vacuum advance at idle and crappy gas mileage. Now I have slightly less crappy gas mileage (9 mpg to 13 mpg in the city... so I guess that's actually about a 50% improverment).

Cheers,

- Will