Inspecting The Fuel Injection Nozzle - Mitsubishi diesel engines Service Manual

ENGINE - INSPECTION / ADJUSTMENT, RUNNING-IN TRIAL AND PERFORMANCE TEST

1.9 Inspecting the fuel injection nozzle

Perform the following inspections and, if faulty,
repair or replace as required.
(1)
Injection valve opening pressure
(a) Install the fuel injection nozzle onto the nozzle
tester. Pump the tester handle to bleed air.
(b) Pump the tester handle at a rate of approx. one
cycle per second while observing the needle of
the tester.
Note: The needle should rise slowly and, during fuel
injection, should vibrate. The pressure at which
the needle starts to vibrate is the injection valve
opening pressure.
(c) If the measured pressure does not conform to
the standard value, disassemble and adjust the
thickness of the washer.
Injection valve opening
pressure
(d) Change in washer thickness by 0.1 mm (0.004
in.) results in a pressure change of 1.0 MPa (10
2
kgf/cm ) [145 psi].
Washers are available in 10 different
thicknesses at intervals of 0.05 mm (0.002 in.)
in the range between 1.25 and 1.70 mm (0.049
and 0.067 in.).
Never touch the spray of fuel from the fuel
injection nozzle as it can cause severe burn.
(2) Inspecting the fuel spray pattern from the fuel
injection nozzle
(a) When inspecting the injection valve opening
pressure using the nozzle tester, also check for
such as clogged nozzle hole, fuel spray pattern
and fuel leakage from the nozzle hole.
(b)
When the tester handle is pumped at a rate of
approx. one cycle per second, fuel should be
sprayed in a fairly straight pattern.
2
Unit: MPa (kgf/cm ) [psi]
Standard value
14.22 to 15.00
(145 to 153)
[2062 to 2176]
Inspecting the injection valve
opening pressure
Replacing the fuel injection nozzle tip
assembly
Good Bad Bad
(Diffused) (Dribbling)
Fuel spray patterns
Nozzle tester
Nozzle tip end
Bad Bad
(Deflected) (Feathering)
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