Isuzu KB P190. Manual - part 249

6C – 32   FUEL SYSTEM 

 

 

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) 

Nozzle Full Lift 

mm (in)

0.25 ± 0.02 (0.0098 ± 0.00008) 

 

 Note: 

 

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

 

 

 

 

Pre-lift confirmation 

1.  With the needle valve at full lift, release the nozzle 

tester handle. 

 

 Note: 

 

The in-line pressure will decrease and needle 
valve lift (as indicated on the dial gauge) will also 
decrease a little. 

 

 

 

040R300008 

 

 

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FUEL SYSTEM    6C – 33 

 

 

2.  Read the needle valve “pre-lift” point from the dial 

gauge indication (once the needle valve has 
descended when the second spring has stopped 
operating). 

Pre-lift measuring point: 
Read the dial gauge at first nozzle opening pressure +approx 
1 MPa (10 kg/cm

2

). 

 Pre-lift mm

 

Pressure Mpa  

(psi/ kg/cm

2

) 

Lift mm (in) 

4JA1T(L) 

20.1 (2,858/205) 

0.04 (0.0016) 

 Note: 

 

This point can be found while the pressure is 
decreasing. 

 

 

3.  Confirm that pre-lift is as specified. 

 

 

 

 

 

4.  If pre-lift is not as specified, replace the pins, lift piece, 

spacer and nozzle assembly as a set with the service 
kit. 

Service kit 

   105017-2990 (Bosch AS) 

897302-3070 (ISUZU) 

 

 

 

 

Second nozzle opening pressure confirmation 

1.  After pre-lift confirmation, operate the nozzle tester to 

increase 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. 

 

 

 

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040H100007

6C – 34   FUEL SYSTEM 

 

2.  Release the nozzle tester handle so that in-line 

pressure decreases. 

 

Note: 

 

The in-line pressure will decrease and needle 
valve lift (as indicated on the dial gauge) will also 
decrease a little. 

 

 

 

 

 

3.  Then, read the pressure gauge indication (second 

nozzle opening pressure) the instant that the dial 
gauge indicates the specified needle valve lift (usually 
pre-lift + 0.05 mm). 

 Second Nozzle Opening Pressure 

 

Pressure Mpa  

(psi/ kg/cm

2

) 

Lift mm (in) 

4JA1T(L) 25.5-27.0 

 

(3768-3911/260-275) 

0.09 (0.0035) 

 
 

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040M100006

FUEL SYSTEM    6C – 35 

 

 

Second nozzle opening pressure adjustment 

If the second nozzle opening pressure is not as specified, 
disassemble the nozzle from the nozzle holder and 
replace the shim until the pressure is as specified. 

CAUTION: 
• 

Because the second opening pressure changes 
when the first opening pressure changes, the 
second opening pressure must be adjusted when 
the first opening pressure changes. 

• 

Use a micrometer to measure shim thickness. 

• 

Use some combination of 3 adjusting shims to 
adjust the pressure. 

 

 

 

• 

Second nozzle opening pressure adjusting shims 

Part No. 
(ISUZU) 

Thickness 

(mm) 

Part No. 
(ISUZU) 

Thickness 

(mm) 

897116-0290

0.10 897116-0380  0.53 

897116-0320

0.20 897116-0390  0.54 

897116-0330

0.30 897116-0400  0.55 

897116-0340

0.40 897116-0410  0.56 

897116-0350

0.50 897116-0420  0.57 

897116-0360

0.51 897116-0430  0.58 

897116-0370

0.52 897116-0440  0.59 

 

 

 

 

 

 

 

Final inspection 

1.  Remove the dial gauge, nut and dial gauge holder. 

 

 

 

 

2.  Remove the adjustment retaining nut and gasket. 

3.  Install the original retaining nut, confirm that the pins 

are inserted fully into the nozzle, and then hand-tighten 
the retaining nut. Then, tighten the original retaining 
nut to the specified torque. 

 

Torque: 7.0 kg·m (50.6 Ib·ft/69 N·m) 

 

 

 

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