| 摘要 |
An evaporative fuel-processing system for an internal combustion engine includes a canister, a charging passage extending between the canister and a fuel tank, a purging passage extending between the canister and the intake system of the engine, an open-to-atmosphere passage for relieving the interior of the canister to the atmosphere, a charge control valve for opening and closing the charging passage, a purge control valve for opening and closing the purging passage, a vent shut valve for opening and closing the open-to-atmosphere passage, and a pressure sensor for detecting pressure within the charging passage. When the engine is in a predetermined operating condition, the interior of the fuel tank is negatively pressurized into a predetermined negatively pressurized state by opening the purge control valve and the charge control valve and closing the vent shut valve. When a predetermined time period has elapsed from the start of the negative pressurization before the interior of the fuel tank is set to the predetermined negatively pressurized state, the purge control valve and the charge control valve are closed, and an abnormality of the fuel tank is determined based on the pressure detected by the pressure sensor immediately before and after the closing of the purge control valve and the charge control valve.
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