a pulse width modulated solenoid - actuated valve and a vacuum - actuated valve for cooperatively associated such that the purge system possesses both accurate control at low purge flows and the capacity for handling much higher flows . the two valves are in parallel paths between the canister and the manifold . below a certain duty cycle of the solenoid - actuated valve , only its path is open . at higher duty cycles , both flow paths are open . an orifice is provided in the flow path containing the solenoid - actuated valve so that as this valve increasingly opens , a vacuum signal at a tap between the orifice and the solenoid - actuated valve also increases . this vacuum signal is applied to a control port of the vacuum - actuated valve to cause the latter to open upon attainment of a certain flow through the solenoid - actuated valve .