The Fuel Vapors Are Routed

WARNING: This page is about a different car, the 2004 Ford RV Cutaway, 2004 Ford Econoline, 2004 Ford E450 Super Duty, and 2004 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

From the fuel tank through the fuel vapor vent valves.
To the evaporative emissions (EVAP) canister through a vapor line.
To the engine when the evaporative emission (EVAP) canister purge valve is opened by the powertrain control module (PCM).