Abstract: An evaporative fuel-processing system for an internal combustion engine is comprised of an evaporative emission control system including a canister, a charging passage extending between the canister and the fuel tank, a purging passage extending between the canister and the intake system of the engine, a purge control valve, and a vent shut valve. A pressure sensor detects the pressure within the evaporative emission control system. The interior of the evaporative emission control system is negatively pressurized into a predetermined negatively pressurized state, by opening the purge control valve and closing the vent shut valve. Then, the purge control valve is closed, and leakage from the evaporative emission control system is checked based on the rate of decrease in negative pressure within the evaporative emission control system over a first predetermined time period.

Abstract: A system for correcting an output from a tank internal-pressure sensor in an evaporative fuel processing device including a fuel tank, and a tank internal-pressure sensor provided in the fuel tank or in an evaporative fuel passage between the fuel tank and a pressure regulating valve. In a condition in which it is difficult to generate an evaporative fuel within the fuel tank, a canister opened to the atmosphere and the fuel tank are brought into communication with each other over a predetermined time. A reference value is reset based on a first detection value detected immediately before the communication, a second detection value detected immediately before releasing the communication, and a reference value stored in a reference value storing device. Thus, it is possible to enhance the accuracy of correction of the output from the tank internal-pressure sensor.

Abstract: An abnormality detection system is provided, which detects abnormality in an evaporative fuel control system for an internal combustion engine. A plurality of temperature sensors are arranged in an evaporative fuel storage device at different locations for detecting the temperature of an adsorbent or in the vicinity thereof within the storage device at the different locations. An ECU controls at least one of charging of evaporative fuel from the fuel tank to the storage device and purging of evaporative fuel from the storage device to the intake system of the engine. The ECU determines the presence or absence of an abnormality in the evaporative fuel control system, based upon output values from the temperature sensors assumed when the control system is operative. A state in which adsorption of evaporative fuel generated in the fuel tank to the adsorbent of the storage device has been completed is detected, based upon the amount of a rise in temperature detected while the charging is being effected.