Of course out of my 100's of pictures, I did not document the routing of this particular vacuum line routing. I think ...maybe... I remember... I had a long hose that snaked all the way over from somewhere on B to the A bank and now I don't? My broken sparkplug adventure extended things past available memory This is a US car, 1987 XJS-C (manufactured in 1986). It think that black box may be the result of some sort of recall in the way back past? (I've not found a picture of this).

 

Is that hose you're holding connected at one end and not the other? Or are you asking about the black round thing that looks like it's missing a vacuum line?

If the latter, on my car, an '87, there is a line that runs from this black thing to the throttle body on the B bank. The other end of the vacuum line runs down and around and ends at the charcoal canister. But, its just inline. It doesn't have the hose coming in at the side the way yours does.

 

The latter yes sorry I should have been more clear! I have not seen a picture of that black box in the second picture and of course I didn't take a picture before disassembly either. It has two long vacuum hoses going into the bottom of the black box - one of them has a one way valve (black with white ring). That black valve in the first picture has large hose at its bottom going into the black box, and a large hose that feeds into a metal pipe on the fuel cooler.

The top of the black box also has a small hose that I think I got right - it has a tee -connecting to B fuel pressure regular and to (I think it is called) the vacuum temperature sensor on the fuel rail(no electrical connection) the forward facing nipple on its left facing nipple a hose connects to vacuum port on the front of the intake.

I got myself into this fix because I needed to replace fuel injector hoses, cam cover gaskets, plugs etc. My air rail / injection system was non functional the rail was severely rusted and broke on removal! So I have deleted that system - perhaps this doesn't matter but just in case this line somehow connected there and it matters.

 

Just an update, according to ChatGPT I needed to connect that to a vacuum source which I have - not sure what that really did. I've not noticed anything really different. Overall running the same well as before - which I am disappointed about
I have a slight right off idle hesitation - which I improved a small bit with a minor adjustment to one of the throttle linkage rods had some slight slack.