Abstract: An abnormality sensing device for an evaporation fuel purge system is equipped with a purge passage that connects a canister to an intake passage of an internal combustion engine, a purge pump, a purge control valve, and a valve component that closes and opens the purge passage at a target passage including at least a first purge passage defined between the purge control valve and the intake passage. An abnormality determining portion detects a physical quantity relevant to a pressure change in the target passage in a determination possible state where the purge control valve allows the evaporation fuel to flow through the first purge passage and where the valve component prohibits the evaporation fuel from being supplied to the intake passage.

Abstract: An abnormality sensing device for an evaporation fuel purge system is equipped with a purge passage that connects a canister to an intake passage of an internal combustion engine, a purge pump, a purge control valve, and a valve component that closes and opens the purge passage at a target passage including at least a first purge passage defined between the purge control valve and the intake passage. An abnormality determining portion detects a physical quantity relevant to a pressure change in the target passage in a determination possible state where the purge control valve allows the evaporation fuel to flow through the first purge passage and where the valve component prohibits the evaporation fuel from being supplied to the intake passage.

Abstract: A control part conducts a pulse width modulation control for a first valve and a second valve in a manner that a sum of a first flow rate of fluid flowing through a first passage and a second flow rate of fluid flowing through a second passage agrees with a target flow rate. When the target flow rate is less than a sum of the maximum of the first flow rate and the maximum of the second flow rate, the control part controls a control timing of a first signal driving the first valve and a control timing of a second signal driving the second valve to be different from each other.