Isuzu N-Series. Manual - part 392

6C-46 FUEL SYSTEM

5. Tighten the injection pump fixing nuts (1) to the

specified torque.

Tighten:
Injection pump fixing nut to 25 N

⋅m (2.6 kg⋅m / 19 lb⋅ft)

Notice:
If there are two marks on the crank pulley, the front side
of mark is for setting BTDC 49

° and the rear side of mark

is for setting TDC.

Injection Timing Check (4HF1-2 model
only)

1. Set No. 1 Cylinder to the TDC in the compression

stroke.

2. Disconnect Injection Pipe.
3. Put down Wax CSD lever, insert a spacer 10 — 12

mm (0.39 — 0.47 in) thick between the plunger and
adjust bolt, and cancel the Wax CSD.

4. Remove the pump rear plug, connect a dial gage

and set the lift at 1 mm (0.039 in).
Special Tool
Measuring device: 5-9940-0145-0

5. Set the crankshaft damper pulley TDC mark to the

pointer or 45

° before TDC.

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Legend

1. Lever
2. Spacer
3. Water hose
4. Wax CSD

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FUEL SYSTEM 6C-47

6. Set the dial gage to the “0” position.
7. Turn the crankshaft leftwise and rightwise a little

and make sure that the needle stays in the “0” po-
sition.

8. Turn the crankshaft in the normal direction and

read the measuring device’s indication at the 12

°

before TDC position.

Notice:
As there is no 12

° mark, set midway between the 11°

and 13

° marks.

Standard value: 0.5 mm (0.0197 in)

Notice:
In case the crank pulley has two marks as illustrated, (1)
BTDC 49

° mark on the second crest and (2) TDC mark

on the third crest (as viewed from the front side), be sure
to set at the mark (2). (If there are two different marks on
one and same crest, set at the mark which comes sec-
ond when rotated in the normal direction.) The mark (1)
is used when installing the injection pump for 4HF1-2.

Injection Timing Adjustment (4HF1-2 model
only)

If injection timing is out of the specified range, follow the
following procedure for adjustment:

1. Loosen injection pump fixing nuts (1) and bracket

bolt (2).

2. Adjust the mounting angle of injection pump:

• If injection timing is too fast, bring the injection

pump closer to the engine.

• If injection timing is too slow, put the injection

pump more distant from the engine.

3. When the dial gage has indicated the specified val-

ue, tighten the fixing nuts and bolt to specified
torque.

Tighten:

• Nut to 24 N

⋅m (2.4 kg⋅m / 17 lb⋅ft)

• Bolt to 48 N

⋅m (4.9 kg⋅m / 35 lb⋅ft)

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6C-48 FUEL SYSTEM

4. Disconnect the dial gage, install and tighten the

plug to specified torque. (Make sure of a coper
washer being attached to the plug)

Tighten:
Plug to 17 N

⋅m (1.7 kg⋅m / 12 lb⋅ft)

5. Release the wax CSD and connect the injection

pipe.

Tighten:
Pipe sleeve nut to 29 N

⋅m (3.0 kg⋅m / 22 lb⋅ft)

Idling Speed Adjustment (Except 4HF1-2
model)

1. Idling Rotation Check

1) Idle the engine.
2) Measure the number of the idling rotations with

a tachometer.

3) When the number of the idling rotations is out-

side the specified value, adjust it with the idling
adjust bolt (arrow-marked).

Number of idling rotations:
550 — 600 rpm
(4HE1-TC)
775 — 825 rpm

Idling Speed Check & Adjustment (4HF1-2
model only)

1. Warm up the engine.
2. Measure idling speed by means of tachometer.
3. If idling speed is out of the standard, adjust with an

idling adjust bolt (indicated by arrow mark).
Idling speed: 575 — 625 rpm

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FUEL SYSTEM 6C-49

INJECTION PUMP DATA

Injection Volume Adjustment (4HF1 Engine)

Test Conditions

4HF1 Engine

Identification Plate and Number

Use the data following the injection pump identification
number to adjust the injection volume.

Item

Condition

Injection nozzle and holder assembly

Bosch AS Part No.: 105118-6051

Injection nozzle

Bosch AS Part No.: 105017-1860

Nozzle holder

Bosch AS Part No.: 105048-3673

Injection nozzle opening pressure

kPa (kg/cm

2

 / psi)

18,142 (185 / 2,631)

Injection line dimensions

Inside diameter

mm (in)

2.0 (0.079)

Outside diameter

mm (in)

6.0 (0.236)

Length

mm (in)

500 (19.7)

Fuel delivery pressure

kPa (kg/cm

2

 / psi)

156.9 (1.6 / 22.75)

Test fuel

SAE Standard Test Diesel Fuel (SAE J967d)

ISO Standard Test Diesel Fuel (ISO 4113)

Test fuel temperature

°C (°F)

40 — 45 (104 — 113)

Identification numbers

101401-7070
101401-7060
101401-7090

101401-7311

Legend

A. Isuzu part No. (Pump assembly No.)
B. Bosch pump assembly No.

N6A0946E