Jaguar Repair: fuel lines/ part ID, fuel pressure regulator, charcoal canister

Question
Hi Howard,
1984 XJ6. Now has 350 installed.I intend using the mechanical fuel pump on the block. There are 2 fuel lines...(one the return,the other the  engine feed) protruding in the trunk. these were originally connected together with some sort of " fuel pressure regulator" I think. This was clamped between the fuel filter and these lines. this piece is 6 sided about 3 inches long 3/4 to inch size. you can unscrew the inlet..which is just a small pin sized orafice...which is why I assume it was a regulator ..for the original pump/injector system. Nothing inside  just the outlet and inlet for the return line. Seems with this piece the fuel would just circulate. How should I handel this return line in the trunk. Actually---if the fuel is supposed to be returned to the tanks...why is this here? I fired the engine with this line open ...and got a trunk full of gas. this orginal piece---with its orafice is no good to me----unless I drill it out...or I go to Home Depot and get a Tee from plumbing--and hook the 2 lines together ...so the fuel ...I guess circulates ...I have also been told...just eliminate the return...its a carburated engine...and the car may not smell like gas. Anyway---sorry iI am so long ..but this part is a puzzel to me--does not seem original jaguar..and why this trunk return line?
thanks Howard for any thoughts

Answer
Hi Ken,

The car has two gas tanks and a fuel return system that returns most of the fuel to the tank that is in use.

You have a carburetor on your 350 or you would not have a mechanical pump on the block. Your mechanical pump may not be capable of supplying enough fuel to bother with a return system. The Jaguar pumped the fuel through a AC cooler and returned most of the fuel to the tank being used.
The fuel still would heat up so a pressure system was used (about 3 PSI) and then vented to a charcoal canister behind the right front head light.

Tell me what you want the system to do and I can probably tell you how to plumb it. Do you want both tanks to act as one with no return system? Or do you want to use the option of using either/or tank with no return? Or even a either/or tank with the return system in tact?

I would advise you keep the vent system intact as you don't need to do anything to it as it is a complete system.

Howard