Here's my test set up for checking out just the fuel system on a K100. Since I had a spare fuel pump, I sat it in a Chinese to-go, large soup container. Ran the fuel output in to the rail. Used a stand alone a battery to power the pump.
Didn't get a picture, but I pulled the injectors out of the engine, but left them connected to the rail, and the electrical harness. Turned the key on, and hit the Starter button. It was a good way to see which injectors were functioning correctly, and which weren't. Soaking all the injectors in the Gunk Parts Cleaner can now.
Yes, gas sprayed all over. Yes, lotsa safety "should-haves". Did have the shop doors opened.