Fuel pressure problem..I'm at a loss.

67Dart273 said
Exactly. Try making a run with a makeshift cap that you KNOW is vented

All 4 of those lines unless modified went into one which came up front for the carbon can setup. If that has been modified/ plugged, "there might not be a vent"

This is in an ebody so the 4 lines come from the tank and run up through the trunk floor into a vapor- liquid seporator. There is a 5th line from the seporator that should go to the breather in the valve cover but, its just open to the atmosphere. I can say the return line from the tank is not hooked up in the engine bay, it just has a cap on it. Also on this type system in an ebody the cap should not be vented.