Howdy,

Did you try cracking each steel line a hair and then pumping? You should see the fuel to "bubble" thru the threads and seep. That way you know you're getting fuel to each injector. Also, you can hook up a slight vacuum on the last injector where you have the stubby return line and draw the fuel thru that way. You will need a source at the very beginning since you cannot suck it thru the IP. Sort of like bleeding brakes if that makes sense