VAPORIZED-FUEL PROCESSING SYSTEM

摘要

A first purge passage is connected to an intake-air passage at a downstream side of a throttle valve. A second purge passage is connected to the intake-air passage at an upstream side of a supercharging device. A first and a second check valve are respectively provided in the first and second purge passages. A control unit determines to which operating condition (from a first to a third operating condition) engine operation corresponds, based on downstream-side and upstream-side pressure of the throttle valve. A change of in-tank pressure of a fuel tank is detected in a condition that an air-communication valve is closed but a purge control valve is opened. The control unit diagnoses which of the valves is not normally operated and whether such valve is fixed to a valve opened or a valve closed position, based on the change of in-tank pressure for each of engine operating conditions.