A vapor impermeable solenoid for a fuel tank isolation valve assembly an outer housing defining an inner cavity, windings configured to generate a magnetic flux when energized, and a flux collector configured to direct the magnetic flux. An armature tube is disposed within the inner cavity inboard of the flux collector and formed of a magnetic and vapor impermeable material configured to prevent fuel vapor molecules from passing therethrough. A pole piece is disposed within the armature tube, and a magnetic armature is disposed within the armature tube and operably coupled to a seal configured to selectively seal a passage that allows fuel vapor to pass to a purge canister. The magnetic armature is configured to move from a first position to a second position when an electric current is applied to the windings.