After a great deal of work in this area recently, I was shocked to smell fuel in my boot a few days ago. I pulled everything out and found that a new source had occurred, this time in the tank exit connector. Coupes of my car's age and earlier had a compression fitting with a J shaped pipe feeding fuel out of the tank, as in this photo (library photo, not my actual car):


The compression fitting can clearly be seen screwed into the short green horizontal tank exit fitting. However, cars made a bit later (about 1988 onwards I have a feeling) had a different tank exit system, using a welded tube as in this photo:


which was connected to a part flexible, part steel J shaped pipe just visible in the above photo, (no. 14 in this diagram) and also shown in close-up in the photo below:
https://parts.jaguarlandroverclassic.../brand/jaguar/

In my case of the earlier system, the compression olive was no longer sealing properly and a VERY slow leak, so slow the leaked fuel was a goo rather than liquid, and was showing just below the fitting.
Conversations with Grant on the hotline produced a solution; which, naturally the Great XJS Prophet of the Southern Cross had many years ago worked out and fitted on his own coupe.

First the bend of the J shaped pipe was cut off, then the flare nut for the compression fitting was expoxied onto the stump of the pipe as shown in the first photo below. Then, when the fitting had set, the threads of the flare nut were liberally coated with epoxy and the fitting was screwed into the tank connection, as shown in the second photo. The third photo shows the permanent and one hopes leak-free exit system thus created.

Flare nut expoxied onto the fuel pipe which has been shortened.

The epoxied fuel supply fitting then has its flare nut threads coated with epoxy and is screwed into the tank connector. In effect, following Grant's advice, I have made a solid tank exit pipe, analogous to the later OEM welded tank exit pipe.

I shall connect the 1/2 inch diameter hose to this shortened pipe with two clips for security, as it has no flared end.

It is Grant's and also my view, that on these earlier cars, the failing compression connector on the tank exit is responsible for a good percentage of fuel smells in the boot. This provides one way of ensuring it gets permanently fixed. The epoxy I used is a marine grade thickened flexy version and it has the great benefit that it does not run or slump having been mixed up. This made doing the job far easier;
https://www.westsystem.com/specialty...poxy-adhesive/

 

I had a new tank from Barratt without that particular olive and as there had never been fuel in the tank I was able to solder all the pita olive joints straight into the tsnk, after making sure the pipes pointed in the correct direction, and also the ones that go through the floor.