| 摘要 |
PURPOSE:To prevent excessive increase in fuel by providing a relief valve and an orifice portion in a communication passage branching from a fuel supply passage located at the discharge side of a fuel pump and by opening the relief valve to return surplus fuel to a fuel tank when a state is reached wherein the engine operation is in a condition of low load and the engine room is at a prescribed high temperature. CONSTITUTION:The fuel pump 51 which is accommodated within a fuel tank 61 comprises a pump housing 4 including a suction port 1 and a discharge port 3, the pump housing 4 having a pump chamber 5 in its interior. The pump chamber 5 is interiorly provided with an impeller 7 being driven by a drive motor. The fuel pump 51 further comprises a casing 10 and is formed with a communication passage 20 for communication between a fuel discharge space in the casing 10 and the interior of the fuel tank 61, an electromagnetic relief valve 21 being disposed in the passage 20. An orifice portion 28 is provided, in the passage 20, at a position thereof which is nearer to the fuel discharge space in the casing 10 than the position of a valve body 24. When a state of idle operation is reached in which the cooling water temperature becomes higher than a prescribed temperature and a throttle valve 42 is substantially closed, an electromagnetic coil 27 of the relief valve 21 is made 'on' to cause the valve body 24 to retreat against the urging force of a spring 25, thereby to open the passage 20. Thus, surplus fuel is returned to the fuel tank 61 via the communication passage 20 for its circulation within the fuel tank 61.
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