Have Ford Questions? Ask a Mechanic for Answers ASAP
Hi, welcome to JA.
The PCM has no role in the fuel cutoff lamp or the inertia switch, but I was mistaken in my earnlier testing procedure on the switch conncetor. The signal is ground to the switch... not power, so we need to make our voltage testing at the relay itself; let me know if you have access to a multimeter. The PCM's job is to trigger the fuel pump relay...it would be a rare occurance for the PCM to fail and not trigger the relay - however it will remain a possibility.
The most common failures when there is no fuel pressure are: faulty fuel pump, faulty inertia switch, blown fuse for relay power supply,or a faulty fuel pump relay By testing at the fuel pump relay connector, we can elliminate 1/2 of the possibilities If you've already replaced the inertia switch with a NEW one, than the fuel cutoff lamp may be comming on due to a bad ground at the inertia switch.
Fuel Pump wiring schematic.
You can jump the pump if you would like, and that will elliminate it's failure; but be sure you only add power to the Black/White wire...which is the pumps hot side.