Subaru 2002 Impreza Service Manual page 26

FUEL LINE
I
Fuel Injection (Fuel System)
C: FUEL INJECTORS
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The MFI system employs top feed type fuel injectors with an air assist feature.
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Each injector is installed in the fuel pipe in such a way that the injector is cooled by fuel.
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The features of this type of fuel injector are as follows:
1) High heat resistance
2) Low driving noise
3) Easy to service
4)
Small size
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The injector injects fuel according to the valve open signal from the ECM. The needle valve is
lifted by the solenoid which is energized on arrival of the valve open signal.
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Since the injector's nozzle hole area, the lift of valve and the fuel pressure are kept constant, the
amount of fuel injected is controlled only by varying the duration of the valve open signal from the
ECM.
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Fuel atomization is enhanced using assist air supplied from the idle air control solenoid valve
passing through the passage formed in the intake manifold at the area in which each injector is
installed. This contributes not only to higher combustion efficiency and higher output but also to
cleaner exhaust emissions.
S2H1943A
(1) Filter
(2) O-ring
(3) Plunger
(4)
Seal
(5)
O-ring
(6)
Connector
FU-10