Isuzu KB P190. Manual — part 249

6C – 32 FUEL SYSTEM

8. Operate the nozzle tester and increase the 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.

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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FUEL SYSTEM 6C – 33

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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6C – 34 FUEL SYSTEM

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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FUEL SYSTEM 6C – 35

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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