Tony,

What you have is a bad primer pump (PP). If the PP is working correctly, it wll push the air out of the IP but you need enough pressure to overcome the IP overflow valve.

I have had completely empty IP and pumping the PP is all it took to prime the IP. By releaseing the banjo fitting, you eliminated the need for the pressure to force open the IP overflow valve because your PP is defective even though it will pump fuel if there is no restriction.

P E H