Maybe try backprobing the injector (installed to the fuel rail and harness) with a multimeter to see if there is a current pulsing through there. If there's no current, then probably the injector wiring is dead (injectors are connected in parallel no?).
Although if it is an electrical problem, it should show up if you run an ECU diagnosis. Can't help you out on how to do that tho, sorry, but it should be really easy and in a gregory's book.
If there is a current going through it or no fault comes up in the diagnosis, then I would say that your injector is not opening properly sand you would need a new one.
Hope that helps you out a bit.