Ahhh...that is a substantially newer unit 99'....I'm not that familiar with the 4.0
but I doubt if they have the 2 pump system like on the gen 1 (1986-1988)...they most likely have just a fuel pump in the tank.
but, in a nut shell, the fuel pressure readings should tell the tale in either case.
you might have better luck posting your question in the 4.0 section of TRS
sorry not much help....and for responding sooo slow...I forget to check my PM box