Isuzu engine 4j series. Manual - part 68

6C - 16  ENGINE FUEL

First nozzle opening pressure adjustment

1. Claim the nozzle holder in a vise.

2. Install the shim, first spring and spring seat in the

nozzle holder.

3. Install the collar, second spring, shim, spring seat and

pushrod in the nozzle holder.

4. Install the pins, lift piece and spacer in the nozzle

holder.

5. Install the pins in the spacer.
6. Install the nozzle on the spacer.

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ENGINE FUEL  6C - 17

7. Hand-tighten the adjustment retaining nut together

with the gasket to the nozzle holder.
Retaining nut:

5-8677-7140-0

Gasket:

5-8677-7139-0

8. Tighten the adjustment retaining nut to the specified

torque.
Torque: 29 - 39 N∙m (3.0 - 4.0 kg∙m)

9. Set the nozzle holder to the nozzle tester.
10.  Operate the nozzle tester and measure the first nozzle

opening pressure.

11.  If the first nozzle opening pressure is not as specified,

disassemble the nozzle holder and replace the shim
until the pressure is as specified.

CAUTION:

Use a micrometer to measure shim thickness.

•

First nozzle opening pressure adjusting shims

Parts No.

Thickness (mm)

1-1534-9042-0

0.40

1-1534-9043-0

0.50

1-1534-9044-0

0.52

1-1534-9045-0

0.54

1-1534-9046-0

0.56

1-1534-9047-0

0.58

1-1534-9048-0

0.60

1-1534-9049-0

0.70

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6C - 18  ENGINE FUEL

Full needle valve lift confirmation
1. Install the gasket and plug on the adjustment retaining

nut.
Gasket:

8-9722-7602-0

Plug:

5-8677-7141-0

2. Position the nozzle holder with the nozzle facing down

and install the dial gauge holder on the nozzle holder.
Dial gauge holder: 5-8677-7142-0

3. Install the nut on the dial gauge holder.

Nut: 5-8677-7143-0

4.  Install the pin to the dial gauge.

Note:

The lengths of the pins do not include the
threaded portions.
Pin (liter=100 mm):

5-8677-7144-0

Dial gauge:

1-8531-7015-0

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ENGINE FUEL  6C - 19

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.

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)

Note:

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

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