Hi all have had this problem since buying a restoration XR3i Cabby:
the previous owner had an ignition live going to the fuel pump RED/BLACK pin where the fuel pump relay should be.... which ran fine but I didn't like it so I pulled all of his dodgy wiring out...
I purchased a NEW Lucas relay (replaces the purple one) and now it primes the pump for about 2-3 seconds I start the car and after that 2-3 seconds of primed fuel it stalls...?
Mine is also the MFi engine and the fuel pump relay runs in conjunction with a speed sensing module Bosch black 6 pin ( 2 rows of 3) part no 0280230113 or 0280230116
Also the RPM rev counter does not work I believe its linked to the fuel relay & speed sensing module