A solenoid valve controls the flow of gas or other fluids, while a solenoid coil is energized by an electric current that creates a magnetic field. When the coil in a fuel solenoid is energized, it causes a plunger inside the coil to move, activating the valve.
Solenoid valves can be classified by the normal state of the valve. In a normally-closed valve, the valve is closed by default. When the coil is energized the valve opens, and when power is removed from the coil it closes. Conversely, in a normally-open valve, the valve closes when energized and opens when power is removed.
Fuel or another medium enters into the valve through an inlet port and flows through the orifice. The media must flow through the orifice and then exit the valve through the outlet port. The orifice is closed and opened by the plunger, which is controlled by an electrical current that determines whether fuel can flow through.