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7. FUEL SYSTEM
7-1 FUEL PUMP
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Fuel suction process
The inside of crankcase becomes vacuum condition in accordance with the piston moving upwards
to the top dead center.
The vacuum pressure, which is introduced via hose into the pulse chamber of fuel pump, pulls the
diaphragm, and then the inside of pump chamber becomes vacuum condition.
As the results, the suction valve is opened and fuel goes into pump chamber frown suction chamber.
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Fuel discharge process
The vacuum pressure of crankcase inside is decreased in accordance with the piston moving
downwards to the bottom dead center.
The vacuum pressure of the pulse chamber is also decreased and the diaphragm moved back by
means of the return spring force.
The fuel in the pump chamber is pressed by the diaphragm, and delivered to the discharge chamber
through the discharge valve.
Suction
Pulsing pressure
Suction chamber
Pulse chamber
Pump chamber
Discharge chamber
Discharge
Pulsing pressure
Pulse chamber
Pump chamber
Summary of Contents for EH63
Page 1: ...SERVICE MANUAL EH63 64 65 and EH72 ENGINES Models PUB ES2158 Rev 08 09 ...
Page 84: ......
Page 85: ...PRINTED IN THE USA ...
