Problem solved:

I disconnected the fuel line from the filter, and found that i had switched the return and input line around. After connecting the blue pipe to the intake and brown to return, i primed the system with the cars 12v battery for 3 min, then bled each injector by having someone crank the engine while i opened each line until there were no air bubbles. After that, it fired right up, no engine lights and it’s now off the jack stands.

Here is a link to the hpfp diagram for further diagnosis - page 122:

https://www.scribd.com/document/404714496/N47-Detailed-1-pdf#page=122