A solenoid valve comprises a housing including an inlet port for fluid communication with a positive pressure source and an outlet port for fluid communication with a negative pressure source; a passage for fluid communication between the inlet port and the outlet port; and an axially bi-directional solenoid-actuated valve in the housing for opening and closing the passage, including an electromagnetically movable valve member having a sealing area exposed to the negative pressure from the outlet port when the valve means is in the closed position; and a diaphragm defining a back pressure chamber in fluid communication with the passage for offsetting the effect of the negative pressure on the exposed sealing area and reducing the electromagnetic force required to move the valve member.
