Komatsu 114E-3 Series Shop Manual page 84

SEN00176-02
High-pressure common rail fuel systems use sole-
noid-actuated injectors. High-pressure fuel flows
into the side of the injector. When the solenoid is
activated, an internal needle lifts and fuel is
injected. The clearances in the nozzle bore are
extremely small and any dirt or contaminants will
cause the injector to stick.
This is why it is important to clean around all fuel
connections before servicing the fuel system. Also,
cap or cover any open fuel connections before a
fuel system repair is performed.
High-pressure fuel is supplied to the injector from
the fuel rail by an injector supply line and a fuel
connector. The fuel connector pushes against the
injector body when the fuel connector nut is tight-
ened. The injector supply line is then connected to
the fuel connector.
The torque and sequence for this joint is critical. If
the nut or line is undertightened, the surfaces will
not seal and a high-pressure fuel leak will result. If
the nut is overtightened, the connector and injector
will deform and cause a high-pressure fuel leak.
This leak will be inside the head and will not be vis-
ible. The result will be a fault code, low power, or
no-start.
If the injector is not fully seated prior to the installa-
tion of the high-pressure connector, the joint will not
seal.
The fuel connector contains an edge filter that
breaks up small contaminants that enter the fuel
system.
a The edge filters are not a substitute for clean-
ing and covering all fuel system connections
during repair.
a Be sure to cap or cover all fuel fittings and
ports.
14
10 Structure, function and maintenance standard
114E-3 Series