•  The piston will be pushed downwards (in the direction of retarded injecting) by the spring force and the fuel outlet hole and housing hole passage will be opened. Therefore the pump internal fuel will be returned through the return pipe to the fuel tank to be normal condition of advanced injecting. The orifice will constantly be opened and the overflow fuel will be returned to the fuel tank through the orifice and return pipe.

•  Excitation current is sent to the solenoid coil according to a signal from the PCM, and as a result the spring force is weakened and the piston is pulled upwards. Then the fuel outlet hole and housing hole passages are shut and the pump internal fuel will only return via the orifice. At this point, the pump internal pressure will suddenly rise and the timer piston will be further pushed to the direction of advanced injecting.

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