It would be helpful here if Morgan had followed Ferrari's (mid engine) practice of suppling fuel to the engine from one tank and having the return line plumbed into the other tank as that ensures fuel (and any additives) circulate throughout the fuel system.
I recall once sitting in the pitlane at Goodwood behind a GT40 replica that had the fuel pumped from one tank to the engine for fuel injection (kinsler system) and then back to the other tank but did not have a sufficient balance pipe between tanks so with the combined fuel in the car at that time of both tanks being greater than the capacity of one tank, a fountain of fuel eruped out of the fuel filler cap as it pushed past the sprung filler cap seal! Quite a drama followed as you can possibly imagine!
