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Group 23 Fuel system
Opening pressure
With the pressure gauge connected, press the injector
tester lever down slowly until the injector opens and
releases fuel. Read off the opening pressure at the
opening instant.
If the value read does not coincide with the specified
value, the setting must be changed. This is done with
shims.
Note. The opening pressure increases or decreases
by about 1 MPa with a change of shim thickness of
0.1 mm.
Checking injectors
Spray pattern
Special tools: 999 9772
1. Pump with injector tester 999 9772 and check the
spray pattern. The fuel spray should be cone-
shaped and aligned with the injector center line.
Fuel drops shall not occur in the spray.
2. Check that the fuel spray has a circular cross-
section.
Sealing
When sealing is checked, investigate the fuel leakage
which can occur between the injector nozzle seat and
the tapered sealing surface in the injector sleeve.
1. Dry the injector nozzle so that it is dry.
2. Pump the pressure up to about 2 MPa below the
opening pressure of the injector (please refer to
Technical Data). Keep the pressure constant for
about 10 sec. and check that no fuel drips out
from the tip of the injector. Damp injectors can be
approved.
Fit a protective plug to the injector’s pipe connection
and over the injector nozzle if it is not to be installed
immediately.
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