Isuzu N-Series. Service manual — part 384
6C-14 FUEL SYSTEM
INJECTION NOZZLE ASSEMBLY
Component
Legend
1. Nozzle cover
3. Injection pipe
2. Leak off pipe
4. Injection nozzle assembly
N6A0839E
FUEL SYSTEM 6C-15
4HE1-TC (Engine)
Removal
Preparation
• Disconnect battery ground cable.
• Tilt the cab.
1. Nozzle Cover
2. Leak-Off Pipe
3. Fuel Injection
1) Loosen the injection pipe sleeve nuts (1).
Do not apply excessive force to the injection
pipes (4).
2) Loosen the injection pipes clips (2).
3) Remove the injection pipe assembly.
Plug the delivery valve holder ports and nozzle
holder (3) ports with caps to prevent the entry
of foreign material.
Legend
1. Nozzle cover
3. Injection pipe
2. Leak off pipe
4. Injection nozzle assembly
N6A0840E
6C-16 FUEL SYSTEM
4. Injection Nozzle Assembly
Mark the nozzle holder assemblies fitting positions
by tagging each nozzle holder assembly with the
cylinder number from which it was removed.
Inspection
Before disassembling the injection nozzle assembly,
check nozzle opening pressure, spray pattern, chatter
and oil leakage.
Opening Pressure
Use a nozzle tester to check the injection nozzle open-
ing pressure.
If the opening pressure is above or below the specified
value, the injection nozzle must be replaced or adjusted.
Spray Pattern
Check the spray pattern
Refer to the illustration.
Spray Condition
• Correct (1)
• Incorrect (Restrictions in orifice) (2)
• Incorrect (Dripping) (3)
If the spray condition is bad, the injection nozzle must be
replaced or adjusted.
N6A0841E
N6A0842E
Injection Nozzle Opening
Pressure
MPa (kg/cm
2
/psi)
4HF1/4HF1-2/4HG1
18.1 (185/2,631)
4HE1-TC
21.6 (220/3,128)
4HG1-T
1st
18.1 (185/2,631)
2nd
21.1 (215/3,057)
N6A0843E
N6A0029E
FUEL SYSTEM 6C-17
Leakage
Hold the tester handle to about 2,070 kPa (21 kg/cm
2
/
300 psi) below the opening pressure. If no drops of fuel
fall from the nozzle tip within 10 seconds, the nozzle is
not leaking.
Chatter
An easily audible chatter at all pump lever speeds
should be heard.
Warning:
WARNING:
TEST FLUID FROM THE INJECTION NOZZLE WILL
SPRAY OUT UNDER GREAT PRESSURE. IT CAN
EASILY PUNCTURE A PERSON’S SKIN. KEEP
YOUR HANDS AWAY FROM THE INJECTION NOZ-
ZLE TESTER AT ALL TIMES.
Disassembly
Clamp the injection nozzle holder in a vice.
1. Flange
2. Retaining Nut
Use a wrench to remove the injection nozzle retain-
er nut.
3. Injection Nozzle
Keep the nozzle along with the needle valve sepa-
rately to maintain the original nozzle to needle
valve combination.
4. Spacer
5. Spring Seat
6. Nozzle Spring
7. Adjusting Shim
Keep the adjusting shims in the original groups to
hold the initial shim to nozzle spring combination.
8. Nozzle Holder Body
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.
Legend
1. Flange
2. Retaining nut
3. Injection nozzle
4. Spacer
5. Spring seat
6. Nozzle spring
7. Adjusting shim
8. Nozzle holder body
N6A0845E
N6A0846E
N6A0847E
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