Fuel Rail Solenoid
WARNING: This page is about a different car, the 2004 Ford Pickup Heritage. However, it is still accessible from the selected car via links, so may be relevant.
The fuel rail solenoid is used to control the alternative fuel flow into the left and right fuel rails. The solenoid is normally closed. When the ALT fuel switch is placed in the ALT position, the solenoid receives VPWR from the inertia fuel shutoff (IFS) switch through the ALT fuel relay. This opens the solenoid allowing CNG fuel flow to the ALT fuel injectors.