2004 ISUZU TF SERIES fuel

FUEL SYSTEM 6C – 31
 First nozzle opening pressure adjusting shims
Parts No. (ISUZU) Thickness (mm)
115349-0420 0.40
115349-0430 0.50
115349-0440 0.52
115349-0450 0.54
115349-0460 0.56
115349-0470 0.58
115349-0480 0.60


115349-0490 0.70


Full needle valve lift confirmation
1. Install the gasket and plug on the adjustment retaining
nut.
Gasket: 026508-1140 (Bosch AS)
894227-6020 (ISUZU)
Plug: 157892-1600 (Bosch AS)



2. Position the nozzle holder with the nozzle facing down
and install the dial gauge holder on the nozzle holder.
Dial gauge holder: 157892-5000 (Bosch AS)



3. Install the nut on the dial gauge holder.
Nut: 157892-1000 (Bosch AS)


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6C – 32 FUEL SYSTEM

4. Install the pin to the dial gauge.
Note:
The lengths of the pins do not include the
threaded portions.

Pin (L=100 mm): 157892-5200 (Bosch AS)
Dial gauge: 157954-3800 (Bosch AS)
185317-0150 (ISUZU)



5. Secure the dial gauge to the nozzle holder using the
nut so that the pin contacts the tip of the first spring
seat.

CAUTION:
 Secure the dial gauge so that a stroke of 2 mm can
be measured.

 Do not over-tighten the nut as the dial gauge shaft
may jam. (Confirm from the dial gauge that the
shaft moves smoothly.)




6. Set the nozzle holder to the nozzle tester and put
needle to zero on the dial gauge.
7. Operate the nozzle tester to bleed any air from inside
the retaining nut and to confirm that no fuel leaks.



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FUEL SYSTEM 6C – 33


8. Operate the nozzle tester and increase the in-line
pressure to 34.3 - 44.1 MPa (350 - 450 kg/cm2) so that
the nozzle’s needle valve moves through its full lift.
Record full lift ‘L’. (Read dial gauge)
Nozzle Full Lift mm (in)
0.25

0.02 (0.0098

0.00008)
Note:
The above operation is used to determine whether
the nozzle seat is worn and whether the nozzle
assembly is in good condition.




Pre-lift confirmation
1. With the needle valve at full lift, release the nozzle
tester handle.

Note:
The in-line pressure will decrease and needle
valve lift (as indicated on the dial gauge) will also
decrease a little.


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6C – 34 FUEL SYSTEM


2. Read the needle valve “pre-lift” point from the dial
gauge indication (once the needle valve has
descended when the second spring has stopped
operating).
Pre-lift measuring point:
Read the dial gauge at first nozzle opening pressure +approx
1 MPa (10 kg/cm
2).
Pre-lift mm
Pressure Mpa
(psi/ kg/cm
2) Lift mm (in)
4JA1T(L) 20.1 (2,858/205) 0.04 (0.0016)
Note:
This point can be found while the pressure is
decreasing.


3. Confirm that pre-lift is as specified.


4. If pre-lift is not as specified, replace the pins, lift piece,
spacer and nozzle assembly as a set with the service
kit.
Service kit
105017-2990 (Bosch AS)
897302-3070 (ISUZU)



Second nozzle opening pressure confirmation
1. After pre-lift confirmation, operate the nozzle tester to
increase in-line pressure to 34.3 - 44.1 MPa (350 - 450
kg/cm
2) so that the nozzle’s needle valve moves
through its full lift.


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FUEL SYSTEM 6C – 35

2. Release the nozzle tester handle so that in-line
pressure decreases.
Note:
The in-line pressure will decrease and needle
valve lift (as indicated on the dial gauge) will also
decrease a little.



3. Then, read the pressure gauge indication (second
nozzle opening pressure) the instant that the dial
gauge indicates the specified needle valve lift (usually
pre-lift + 0.05 mm).
Second Nozzle Opening Pressure
Pressure Mpa
(psi/ kg/cm
2) Lift mm (in)
4JA1T(L) 25.5-27.0
(3768-3911/260-275) 0.09 (0.0035)


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6C – 36 FUEL SYSTEM


Second nozzle opening pressure adjustment
If the second nozzle opening pressure is not as specified,
disassemble the nozzle from the nozzle holder and
replace the shim until the pressure is as specified.
CAUTION:
 Because the second opening pressure changes
when the first opening pressure changes, the
second opening pressure must be adjusted when
the first opening pressure changes.

 Use a micrometer to measure shim thickness.
 Use some combination of 3 adjusting shims to
adjust the pressure.



 Second nozzle opening pressure adjusting shims
Part No.
(ISUZU) Thickness
(mm) Part No.
(ISUZU) Thickness
(mm)
897116-0290 0.10 897116-0380 0.53
897116-0320 0.20 897116-0390 0.54
897116-0330 0.30 897116-0400 0.55
897116-0340 0.40 897116-0410 0.56
897116-0350 0.50 897116-0420 0.57
897116-0360 0.51 897116-0430 0.58
897116-0370 0.52 897116-0440 0.59




Final inspection
1. Remove the dial gauge, nut and dial gauge holder.



2. Remove the adjustment retaining nut and gasket.
3. Install the original retaining nut, confirm that the pins
are inserted fully into the nozzle, and then hand-tighten
the retaining nut. Then, tighten the original retaining
nut to the specified torque.
Torque: 7.0 kg·m (50.6 Ib·ft/69 N·m)


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FUEL SYSTEM 6C – 37

4. Set the nozzle holder to the nozzle tester and check
first nozzle opening pressure, spray condition, seat oil
tightness and each part for oil leaks.
5. When replacing the nozzle, replace the nozzle, lift
piece, pins and spacer as a set with the nozzle service
kit.
CAUTION:
Pre-lift will not be as specified if only the nozzle is
replaced.


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6C – 38 FUEL SYSTEM
SPECIAL TOOLS
ILLUSTRATION TOOL NUMBER TOOL NAME
5-8840-2602-0
(J-39765) Remover: fuel pump retainer ring