| 摘要 |
In a fuel vapor processing apparatus of a fuel tank for an internal combustion engine, fuel vapor in the fuel tank is supplied to a fuel vapor collecting canister filled with an absorbent, and is absorbed and collected therein, and the absorbed fuel in the canister is introduced into the downstream of a suction air throttle valve in a suction air passage through a control valve. The fuel vapor processing apparatus comprises a three-way valve having three openings which are connected to an air port of the canister, an upper air chamber of the fuel tank, and an air release port, a pressure sensor provided in such a manner that the pressure sensor is closer to the fuel tank than the control valve is, and a control unit which operates the three-way valve so as to communicate the air port of the canister with the upper air chamber of the fuel tank and to introduce a suction negative pressure into piping portions of the fuel vapor processing apparatus through the control valve, so that when the pressure in the piping portions reaches a predetermined value, the control unit closes the control valve, and that when a change of signals transmitted from the pressure sensor in accordance with time thereafter exceeds a predetermined range, the control unit judges it as abnormality.
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