Fuel Fill Check Valve
WARNING: This page is about a different car, the 2002 Saturn LW200, 2002 Saturn L200, and 2002 Saturn L100. However, it is still accessible from the selected car via links, so may be relevant.
The fuel fill check valve is plastic welded into fuel tank inlet; this one-way check valve prevents liquid fuel from rushing back up tube when fuel delivery is stopped. It also aids in controlling fuel tank vapors from traveling back up filler tube. It is not serviceable. If defective, fuel tank assembly must be replaced.