Evaporated fuel processing device

An evaporated fuel processing device configured to adsorb evaporated fuel in a fuel tank to a canister and to feed the adsorbed evaporated fuel to an engine, in which a flow control valve is used as a valve to be installed in a pathway connecting a fuel tank and a canister, and in which the flow control valve is held in a valve-closed condition when a stroke amount corresponding to an axial travel distance of a valve movable element to a valve seat is equal to or less than a predetermined amount from an initial condition to hold the fuel tank in a hermetically closed condition, comprising:

• an inner pressure sensor configured to detect a pressure in an interior space of the fuel tank as an inner pressure;
• a valve-opening start position determination means configured to change the stroke amount of the flow control valve from an initial condition in a valve-opening direction, and configured to determine a valve-opening start position of the flow control valve based on a requirement that a range of variation of the inner pressure detected by the inner pressure sensor is equal to or greater than a predetermined value;
• a learning means configured to store the valve-opening start position determined by the valve-opening start position determination means as a learned value that is used when a valve-opening control of the flow control valve is performed;
• and
• a prohibition means configured to prohibit the valve-opening start position determination means from determining the valve-opening start position when the inner pressure detected by the inner pressure sensor falls within a predetermined pressure range relative to the atmospheric pressure.