Yanmar 3JH4E Service Manual page 48

2. Inspection and Adjustment
(2) Check the injection spray condition of a fuel nozzle
1) Injection pressure measurement
Standard
21.1-22.1
(215-225)
[Notice]
As for the opening pressure of the brand-new fuel
nozzle, about 0.5MPa (5kgf/cm) declines by the
engine operation for about 5 hours because of the
initial wear-out of a spring etc. Therefore, adjust
0.5MPa (5kgf/cm) higher than the standard value of
the above table when adjusting a new fuel nozzle of a
spare part.
Remove carbon deposit at the nozzle hole thoroughly
before measurement.
a) Connect the fuel injection valve to the high pressure pipe of the nozzle tester.
b) Operate the nozzle tester lever slowly and read the pressure at the moment when the fuel
injection from the nozzle starts.
c) If the measured injection pressure is lower than the standard level, replace the pressure adjusting
shim with a thicker one.
Thickness of pressure adjusting shims
0.13, 0.15, 0.18, 0.4, 0.5, 0.8
Wear protective glasses when testing injection from the fuel injection
nozzle. Never approach the injection nozzle portion with a hand. The oil
jetting out from the nozzle is at a high pressure to cause loss of sight or
injury if coming into careless contact with it.
2
MPa(kgf/cm )
mm
The injection pressure is increased by approx. l.9 MPa (l9 kgf / cm
when the adjusting shim thickness is increased by 0.l mm.
Injection nozzle
Injection pressure measurement
(
with nozzle tester
Injection pressure adjustment
32
Nozzle tester
)
2
),