[Unknown1]

Thought id update with a resolution in case anyone else finds this useful. At a second inspection ive discovered the "2nd valve" on the fuel pump which isn't used on this model vehicle and is meant to be sealed/blanked off by Bosch, in turn hasn''t been, creating a vacuum

So its not allowing pressure to build within the pump assembly to send the fuel.

Glad i found the issue- now speaking with Bosch / supplier to find out where to go from here.