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Fuel pressure control system
As the amount of injected fuel supply to the engine is controlled according to the injection signal (to determine how long
the injector injects fuel) sent to the injector by the ECM, it is also necessary to control the fuel pressure. Otherwise, fuel
injection increases when the fuel pressure is high and decreases when it is low even though the fuel injection time is the
same.
Furthermore, since fuel injection takes place in the intake manifold, if the fuel pressure is kept constant, the amount of
injected fuel supply increases when the manifold vacuum is high and decreases when it is low. Therefore, to keep the
air/fuel ratio at a proper level, a pressure regulator is used to control the fuel pressure for more accurate control over the
amount of fuel injection.
Pressure regulator
The pressure regulator controls the fuel pressure applied to the injector so that it is kept 2.9kg/cm2 higher than the ambi-
ent air pressure. When the fuel pressure rises more than 2.9kg/cm2 higher than the air pressure, the diaphragm is
pushed up to send back an excess fuel to the fuel tank through the return pipe so that the fuel pressure is constantly kept
2.9kg/cm2 higher than the air pressure.
Pulsation damper
Although the fuel pressure is controlled by the pressure regulator so that it stays 2.9kg/cm2 higher than the air pressure
in the manifold, it varies slightly when fuel is injected by the injector. The pulsation damper absorbs such slight variation
by function of spring and diaphragm in it.
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