Leak detector for evaporated fuel

An evaporated fuel leak detector for detecting leakage of an evaporated fuel generated in a fuel tank, the detector comprising:

• a differential pressure valve including a detection port, an atmosphere port, a pressure chamber and a valve member, wherein the detection port connects to a fuel tank side, wherein the atmosphere port is opened to atmosphere, wherein the valve member is 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, and wherein 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 pump for sucking a detection port side of the differential pressure valve so as to reduce pressure on a fuel tank side;
• and
• pressure detection means for detecting pressure on a detection port side of the differential pressure valve.