New Injector pump

[rScotty]

You need to solve the air problem before blaming the pump or the people who worked on it just yet. Maybe you need to get a little "creative with a temporary fuel supply to eliminate some of the likely possibilities.
I doubt the injectors have anything to do with that problem. Leave them alone until you sort out the supply problem.

I like Harry's idea. Air can only enter if fluid leaves. And fluid can only leave by two paths:
One path for fluid to excape is past the injector nozzles, and the other path is somewhere unknown but must be in the pumping system supplying the injectors.

If you rig up an overhead bottle to feed the injector pump as Harry suggests, then it becomes difficult for fluid to bleed off in the supply side/pump side direction. Some accurate marks on that overhead bottle might even tell a bit more.

rScotty