Isuzu N-Series. Manual - part 611

6C-14 ENGINE FUEL

INJECTION NOZZLE

Component

4JB1 / 4JG2

Legend

1. Injection pipe

3. Injection nozzle

2. Leak off pipe or hose

N6A3401E

ENGINE FUEL 6C-15

Removal

Preparation:

• Disconnect battery ground cable.

1. Injection Pipe

• Release injection pipe clip.
• Loosen the flare nut on the injection pump side.
• Loosen the flare nut on the injection nozzle side,

disconnect and put aside the pipe.

2. Leak off Pipe or Hose
3. Injection Nozzle

Disassembly (4JG2 Engine)

• Grip nozzle holder with a vise, loosen retaining nut

and disassemble.

• Loosen holder nut and remove the nozzle.

Caution:

• Be careful not to damage the needle valve.
• Remove spacer, positioning pin, and push rod.

• Remove spring and adjusting shim.

Caution:

• Wash all the parts removed and arrange them on a

cylinder basis, care should be taken not to miss
any parts.

• Soak the nozzle assembly in a parts receptacle

filled with light oil.

• Care should be taken not to miss shim, if used.

Inspection (4JG2 Engine)

Nozzle

• Soak the nozzle removed in clean light oil, wash

nozzle body and needle valve separately, and
check and see that the needle valve slide smoothly
in the nozzle body.

Caution:

• If the needle valve does not slide smoothly repair

or replace with a new nozzle assembly.

N6A3736E

N6A3737E

N6A3738E

N6A3739E

6C-16 ENGINE FUEL

Nozzle Lapping Procedure

• Apply thinly a compound (Oxide chrome kneaded

with animal oil) to the seat of needle valve and lap.

Caution:

• Excess compound may cause worn needle valve,

and be sure to wash out the compound after lap-
ping.

Nozzle Body & Needle

• Check nozzle body and end for seizure.

If significantly seized, replace as a nozzle assem-
bly basis. Also replace as a nozzle assembly basis,
if needle valve end is deformed or seized.

Caution:

• If either nozzle body or needle valve is faulty, re-

place with a new nozzle assembly.

Reassembly (4JG2 Engine)

To reassemble, follow the removal steps in the reverse
order, noting the following point.

Caution:

• Be careful to fit spacer because positioning pins

are set off.

Legend

1. Oxidized chrome kneaded with animal oil
2. Nozzle body
3. Needle valve

N6A3740E

N6A3742E

N6A3741E

N6A3743E

ENGINE FUEL 6C-17

f

• Install retaining nut and tighten nut to the specified

torque.

Tighten:
Nut to 39 N

⋅m (4.0 kg⋅m/32 lb⋅ft)

Adjustment of Injection Opening Pressure
(4JG2 Engine)

• Set nozzle holder assembly on a nozzle tester.
• Apply hydraulic pressure by operating tester han-

dle, and make sure fuel cam be injected under the
following pressure.

Caution:

• If not injected under the specified pressure, adjust

with adjusting shim.
Types are available in the 1.0 — 1.75 mm (0.039
— 0.069 in) thickness range (on a 0.01 mm
(0.00003 in) basis).

• Unless extremely deformed spray in seen, there is

no problem.

Legend

1. Nozzle holder
2. Adjusting shim
3. Nozzle spring
4. Positioning pin
5. Push rod
6. Spacer
7. Nozzle
8. Holder nut
9. Retaining nut

N6A3744E

Kpa (kg/m

2

/psi )

14,710 (150/2,133)

N6A3745E

N6A3746E