Fuel Pressure Regulator
WARNING: This page is about a different car, the 2006 Ford Pickup, 2006 Ford F550 Super Duty, 2006 Ford F450 Super Duty, and 2006 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
Fuel pressure in the cylinder head fuel galleries is controlled by a fuel pressure regulator. The fixed orifice is an air bleed. It is the highest point in the fuel system. It allows the air behind the fuel pressure regulator to be vented to the fuel tank rather than ingested in the fuel galleries. The fuel pressure regulator contains a spring-loaded poppet valve, which opens to allow excess fuel to return to the fuel-conditioning module. Once back to the fuel-conditioning module, the fuel is sent back to the fuel tank or to the engine, if the fuel-conditioning module is in recirculation mode.