The P7100 doesn't happen to have a fuel cutoff solenoid like the VE pump does it?
I totally forgot about hooking that up on my engine and it wouldn't fire up.
I forgot about the fuel shut also and had one go bad on one of my boats 5.9's, It was sticky and did not open sometimes and was a pain to to diagnose too! You can run power to it and watch how the piston moves or maybe listen to it.
Doug
Another thing to check, for sure.
You may have just had too much air in the injector lines themselves and it took a while to get them all bled out.