A detector for detecting evaporated fuel leakage from a fuel tank is connected to the fuel tank through a canister for absorbing evaporated fuel. When an engine is not in operation, air in the fuel tank is sucked by a pump installed in the detector. If the pressure in the fuel tank decreases to a predetermined level, it is determined that the evaporated fuel leakage is within a permissible range. An orifice passage, formed in the detector, connecting a tank passage to a sensor passage communicating with a sensor chamber where a pressure sensor is disposed is slanted relative to the tank passage to shorten the passage distance up to the pressure sensor. Further, the orifice passage is connected to the sensor passage at an obtuse angle to reduce a pressure loss in the passages. Thus, the leakage of the evaporated fuel is surely detected while making the detector compact.

A fuel handling apparatus with a purge system, a first communication passage, and a second communication passage with a greater pressure loss than the first communication passage. A check device is coupled to the second communication passage for checking a leak of evaporative fuel from the purge system. A pump is included, and a selector device is included for switching fluid communication of the pump between one of the first communication passage and the second communication passage. A controller controls the selector device to allow fluid communication between the first communication passage and the pump and then controls the pump to produce the pressure difference for forcible purging. The controller further controls the selector device to allow fluid communication between the second communication passage and the pump, and then controls the pump to produce the pressure difference and controls the check device for leak checking.

An evaporated fuel leak detector detects leakage of an evaporated fuel generated in a fuel tank. The detector includes: a differential pressure valve, a pump for sucking a detection port side to reduce pressure on a fuel tank side, and pressure detection means for detecting pressure on a detection port side. The valve includes a detection port connecting to a fuel tank side, an atmosphere port opened to atmosphere, a pressure chamber and a valve member displaceable in accordance with differential pressure between the detection port and the pressure chamber for connecting and disconnecting a connection between the detection port and the atmosphere port. The valve member disconnects between the detection port and the atmosphere port in a case where pressure of the pressure chamber becomes larger than pressure of the detection port by a predetermined pressure.

A leakage detecting device is connected to an evaporating fuel processing apparatus to detect leakage of evaporating fuel in a ventilation apparatus that includes an electric pump, a fuel tank, and a filter. The electric pump includes a pump portion and a motor portion. The pump portion is capable of generating at least one of pressurizing force and de-pressurizing force. The motor portion drives the pump portion. The filter absorbs fuel evaporating in the fuel tank. The leakage detecting device generates pressure difference between the inside of the ventilation apparatus and the outside of the ventilation apparatus in accordance with the pressurizing force and the de-pressurizing force generated using the electric pump to detect a leakage condition of the ventilation apparatus. The leakage detecting device includes a rotation speed controlling means that controls rotation speed of the motor portion at a predetermined rotation speed.