FiTech EFI system

I don't know man I would be looking at a restriction, somewhere particularly at the pickup. I'm not familiar with that setup. Is there ANY possibility that the pickup can "suck shut?"

The other "first thing I'd check" is to be ABSOLUTELY SURE the pump is actually getting full voltage, at least for your test. DON'T FORGET the ground side!!!!

What is that setup using for connections at the tank? Ground? etc.

Other thing you might consider (not sure how you are setting it up) is change the test conditions. Are you checking pressure "out of the car?"