Hello Mate, on the back of the fuel pump (inside the large nut/19mm I think)
the is a small one way vavle which stops the fuel draining back to the tank
once the ignition is turned off. It's the same part on all the early Mfi fords
(orions,xr3i's etc) so before you start playing around with metering heads
get one from a scrappy cos even if you have to buy the whole pump to get it
it'll only be a tenner. Good luck.