The black box thingy is a hydro electric pressure actuator. It shouldnt ever cut the supply off, more likely to stop adjusting the fuelling if anything.

There seems to be a lot of peopel with this phantom fault at the moment, and from the way things have been going it could well be the pump is lazy, the fuel pressure has to exceed that of the injectors, so if the pressure drops just a little you wont get fuelling out of the injectors. Try taking an injector off and seeing if the fuel is very pressurised coming out (if it does at all)