I have a 1991 XJS Conv. 5.7 Carb 700R4 The fuel return line and charcoal canister are all but missing. How can I remove what is left of the system along with the sump tank and make it work properly with a mechanical pump?
You don’t really need either for the car to run.
The return line is for FI. Connects the fuel pressure regulator returns x’s pressure fuel back to the tank.
The canister is a part of the closed fuel tank vent system. Leaving the line from the tank open at the canister merely reverts it to old tech. Vented to the atmosphere.
If desired, you could devise a “purge” by a connection to the intake.