i have a Escort RS Turbo series 2 and wont run when you start it, it chucks out black smoke then stalls and is massivley over fueling

then if i unplug the plug at the rear of the metering unit with the black unit on (fuel pressure acuator) it runs absolutley fine

i have tried 2 other metering units and changed the wiring loom and its still the same!

im totally stuck and havn't a clue whats going on and what to do next?

i would carry on running with it unplugged but i know it gives you extra fuel when boost comes on so i don't want to run it lean so please what do i try next people??