Refueling control system for internal combustion engine

A refueling control system for an internal combustion engine, comprising:

• a fuel tank;
• a vapor pipe communicating with a gas region inside the fuel tank;
• a shut-off valve disposed in the vapor pipe, the shut-off valve being configured to be drive by a step motor;
• a fuel filler lid configured to be opened and closed by an actuator;
• and
• an electronic control unit configured to, when the fuel filler lid is to be opened, i) drive the shut-off valve such that the shut-off valve is opened to a target opening degree that is set in advance, ii) close the fuel filler lid by controlling the actuator when an opening degree of the shut-off valve is less than a set opening degree that is set in advance, and iii) open the fuel filler lid by controlling the actuator when the opening degree of the shut-off valve is greater than or equal to the set opening degree, the electronic control unit being configured to set the set opening degree such that the set opening degree when an opening speed of the shut-off valve is low is greater than the set opening degree when the opening speed of the shut-off valve is high.