Yanmar 3TNV76 - Adjusting Fuel Injector Pressure

FUEL SYSTEM
TNV IDI Service Manual
7-27
Fuel Injectors
7. Perform a nozzle valve slide test:
(a) Wash nozzle body and valve in clean diesel
fuel.
(b) While holding the nozzle body vertical, pull
the nozzle valve about 2/3 of the way out
(Figure 7-34).
(c) Release the valve. It should fall smoothly to
its seat by its own weight.
Figure 7-34
Replace the fuel injector assembly if it fails any
inspection.
Adjusting Fuel Injector Pressure
The fuel injectors open when pressure reaches a
predetermined pressure threshold. They close
when the pressure is reduced below that threshold.
The pressure threshold can be adjusted by adding
or removing shims (Figure 7-35, (4)).
1 –Return Fuel Fitting Nut
2–Fuel Return Fitting
3 –Injector Body
4 –Pressure Adjusting Shims
5–Spring
6 –Spring Seat
7 –Valve Stop Spacer
8 –Nozzle Valve
9 –Nozzle Body
10– Nozzle Case Nut
Figure 7-35
The injection pressure will change by
approximately 100 - 142 psi (0.69 - 0.98 MPa;
7 - 10 kgf/cm
2
) for every 0.004 in. (0.1 mm) shim
thickness.
See the parts catalog for available shims.
1. Disassemble the fuel injector assembly. See
Disassembly and Inspection of Fuel Injectors
on page 7-26.
2. Remove or add adjusting shims as needed.
3. Reassemble the fuel injector assembly. See
Reassembly of Fuel Injectors on page 7-28.
Fuel Injector Shim Kit
Yanmar Part No. 129901-53800
(Includes one each of the following shims)
129901-53810 0.0039 in. (0.10 mm)
129901-53820 0.0079 in. (0.20 mm)
129901-53830 0.0118 in. (0.30 mm)
129901-53840 0.0157 in. (0.40 mm)
129901-53850 0.0197 in. (0.50 mm)
129901-53860 0.0205 in. (0.52 mm)
129901-53870 0.0213 in. (0.54 mm)
129901-53880 0.0220 in. (0.56 mm)
129901-53890 0.0228 in. (0.58 mm)
129901-53900 0.0315 in. (0.80 mm)
033109-00X
0002093
0002214
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
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