Ford computers only turn the fuel pump on for 2 seconds when key is first turned on.
It won't start again until RPMs are above 400, this is a safety features in case fuel line breaks, broken fuel line would cause engine to go below 400RPMs, it would stall, lol, and pump would shut off instead of pumping fuel out the broken line.
If you cycle the key on and off a few times the noise should changed, as the pressure in the system builds the pump can't push anymore fuel in, so it would sound quieter more muffled.
You can pull out the Fuel Pump relay and put a jumper in there.
have a look here: Automotive Relays - Electric Circuit
All automotive relays are the same, same layout just different load ratings and voltages
You want to jump slot 30 to 87, those are the "load" contacts
85 and 86 are the coil contacts, used to CLOSE the "load" contacts