I've tried two different gauges, have driven with both of them attached. Both required bleeding before registering fuel pressure, and both showed the same readings. Both gave me 35 on startup (after bleeding the gauges and spraying fuel everywhere), and then both fell to 30 while driving. Fuel pressure would slowly fall after truck was shut off.
FSM says 49 psi.
I have never bleed a fuel or oil pressure gauge. If the fsm says 49 psi than either it is the pump or your gauge. You need correct fuel pressure or it will not run right period.
