Isuzu KB P190. Manual - part 247

6C – 24   FUEL SYSTEM 

 
 
 
 
 
 
 
 

13. Throttle Position Sensor Harness Connector 

(4JA1TC/4JH1TC only) 
Reconnect the harness connector to the throttle position 
sensor. 

14. Power Steering Pump Bracket 

 

 

15. Fan 
16. Vacuum Hose 

Connect the vacuum hose to the EGR valve and the 
intake throttle. 

  

 

Euro under

Euro I 

Euro II 

Euro III 

4JA1L without  with  with  Not 

used 

4JA1TC 

Not used 

Not used 

Not used

With cooler

(EGR cooler)

4JH1TC without 

with 

with 

With  

(EGR cooler)

 

 
17. Accelerator Control Cable 

1)  Connect the accelerator cable to the injection pump 

(4JA1T) the intake throttle. (4JA1TC/4JH1TC only) 

18. Power Steering Pump Assembly 
19. Drive Belt 

Install the drive belt and adjust the belt tension.  

20. Battery 

 
 

FUEL SYSTEM    6C – 25 

INJECTION NOZZLE (4JA1L) 

 DISASSEMBLY 

 

 

RTW76CMF000401 

 

 

Disassembly Steps 

 

 

  

1. 

Retaining 

nut 

 

2. 

Nozzle & pin 

 

3. 

Spacer & pin 

 4. 

Lift 

Piece 

 5. 

Spring 

seat 

 6. 

Push 

rod 

 

7. 

Shim (Second nozzle opening 

pressure adjustment) 

 8. 

Second 

spring 

   9. 

Collar 

 10. 

Spring 

seat 

 11. 

First 

spring 

 

12. 

Shim (First nozzle opening 

pressure adjustment) 

 

13. 

Nozzle holder body 

 14. 

Eye 

bolt 

 
 
 

 

Important Operations 

Injection nozzle adjustment is possible only on the 4JA1L 
engine. 

The two-spring nozzle holder has been developed to 
reduce NOx (Nitrogen Oxides) and particulates from direct 
injection diesel engine exhaust. 

Before disassembly remove carbon deposit from nozzle 
and nozzle holder using a wire brush and wash the outside 
nozzle holder assembly. 

Caution:  

Do not touch nozzle holes with the wire brush during 
cleaning it. 

Disassemble the nozzle holder assembly to numerical 
order. 

6C – 26   FUEL SYSTEM 

 REASSEMBLY 

 

 

RTW76CMF000501 

 

 

Reassembly Steps 

 

 

 

 

1. 

Nozzle holder body 

 

2. 

Shim (First opening pressure 

adjustment) 

 3. 

First 

spring 

 4. 

Spring 

seat 

 5. 

Collar 

 6. 

Second 

spring 

 7. 

Push 

rod 

 

8. 

Shim (Second opening pressure 

adjustment) 

  9. 

Spring 

seat 

 10. 

Lift 

Piece 

 

11. 

Spacer & pin 

 

12. 

Nozzle & pin 

 13. 

Retaining 

nut 

 14. 

Eye 

bolt 

 

 
 
 
 
 
 
 
 
 
 

 

Important Operations 

The nozzle holder is adjusted as the components are 
reassembled in the sequence above. 

As adjustment of the two-spring nozzle holder is made in 
hundredths of a millimeter, clean the parts thoroughly in 
light oil to completely remove any dirt or foreign matter. 

FUEL SYSTEM    6C – 27 

 

REASSEMBLY AND ADJUSTMENT PROCEDURE 

 

1 

First nozzle opening pressure adjustment 

 

Adjust the first nozzle opening pressure using the shim. 

 

 

 

 

2 

Full needle valve lift confirmation 

 

Confirm the full needle valve lift in accordance with the 
closed method.

 

 

 

 

3 

Pre-lift confirmation 

 

 

 

 

Confirm pre-lift in accordance with the closed method. 

 

CAUTION: 
If not as specified, replace the nozzle assembly, lift 
piece, pins and spacer using the nozzle service kit. 

4 

Second nozzle opening pressure  

confirmation 

 

Confirm the second nozzle opening pressure in accordance 
with the closed method. 

 

 

 

 

5 

Second nozzle opening pressure 

adjustment 

 

Adjust the second nozzle opening pressure using the shim.

 

 

 

 

6 

Final inspection 

 

Confirm the condition of the fuel spray with the nozzle and 
nozzle holder assembled. 

 
 
 
 
 
 
 

First nozzle opening pressure adjustment 

 

Nozzle needle valve full-lift 

0.25 mm (0.0098 in) 

Nozzle needle valve pre-lift 

0.04 mm(0.0016 in) at 20,000 kPa (2901 psi, 204 kg/cm

2

) 

Nozzle pressure 

 

4JA1T(L) 

1st Stage 

19.1 MPa (2759 psi, 194 kg/cm

2

) 

 

2nd Stage 

25.5-27.0 MPa (3768-3911 psi, 260-275 kg/cm

2

) 

 
NOTE: Only 4JA1L can perform adjustment of a nozzle.