What I see, the green/white wire should be your + power to the injector and the yellow/grey would be the switched ground lead going to the motronic controller.
Disconnect the wire connector from both injectors and then you should be able to read +12 on the green/white with ignition turned on(don't try to start it, just key on, kill switch on, stand up). You may only be able to see power on the injector when the fuel pump is actually running. Like the K, the pump may only prime for a few seconds and then turn off. You may need someone to turn on the key while you have your meter connected so you can read it at the same time.
If you don't see any power while the pump is running, you most liklely have a wiring problem with the green/white wire. If the bike had been outside, in a shed or something, not unheard of to have mice eat on wiring.
I'm not versed with boxers either, but like you, I would think that the motornic would work the same as on the bricks. Hall sensors tell the motronic when to run the fuel pump and when to fire the injectors, and spark plugs.
