fuel pressure ISUZU TF SERIES 2004 Owner's Manual

6C – 18 FUEL SYSTEM
FUEL FILLER CAP




RTW36CSH000401
Legend

(1)
Pressure Valve

(2)
Vacuum Valve

(3)
Seal Ring


General Description
A vacuum valve and pressure valve are built into the fuel filler
cap which adjusts the fuel pressure in the fuel tank to prevent
fuel tank damage.


Inspection
The fuel filler cap must be inspected for seal condition.
The fuel filler cap must be replaced if found defective

CAUTION: A replacement fuel filler cap must be the same
as the original. The fuel filler cap valve was designed
primarily for this application and must be replaced with
the same type or decreased engine performance may
occur.

6C – 26 FUEL SYSTEM
INJECTION NOZZLE (4JA1L)
DISASSEMBLY




















080L200009


Disassembly Steps
1.
Retaining nut 9.
Collar
2.
Nozzle & pin 10.
Spring seat
3.
Spacer & pin 11.
First spring
4.
Lift Piece 12.
Shim (First nozzle opening
pressure adjustment)
5.
Spring seat 13.
Nozzle holder body
6.
Push rod 14.
Eye bolt
7.
Shim (Second nozzle opening
pressure adjustment) 15.
Gasket
8.
Second spring



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.

FUEL SYSTEM 6C – 27
REASSEMBLY




















080L200010


Reassembly Steps
1.
Nozzle holder body 9.
Spring seat
2.
Shim (First opening pressure
adjustment) 10.
Lift Piece
3.
First spring 11.
Spacer & pin
4.
Spring seat 12.
Nozzle & pin
5.
Collar 13.
Retaining nut
6.
Second spring 14.
Gasket
7.
Push rod 15.
Eye bolt
8.
Shim (Second opening pressure
adjustment)











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.

6C – 28 FUEL SYSTEM

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/cm2)
Nozzle pressure
4JA1T(L) 1st Stage 19.1 Mpa (2759 psi, 194 kg/cm2)
2nd Stage 25.5-27.0 Mpa (3768-3911 psi, 260-275 kg/cm2)

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

FUEL SYSTEM 6C – 29


Injection Nozzle Adjustment
First nozzle opening pressure adjustment
1.Clamp the nozzle holder in a vise.



2. Install the shim, first spring and spring seat in the
nozzle holder.



3. Install the collar, second spring, shim, spring seat and
pushrod in the nozzle holder.



4. Install the pins, lift piece and spacer in the nozzle
holder.



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6C – 30 FUEL SYSTEM

5. Install the pins in the spacer.
6. Install the nozzle on the spacer.



7. Hand-tighten the adjustment retaining nut together
with the gasket to the nozzle holder.
Retaining nut: 157892-3200 (Bosch AS)
Gasket: 157892-5100 (Bosch AS)
(Bosch AS = Bosch Automotive Systems Corporation)



8. Tighten the adjustment retaining nut to the specified
torque.
Torque: 5.1 kg·m (36.9 Ib·ft/50 N·m)




9. Set the nozzle holder to the nozzle tester.
10. Operate the nozzle tester and measure the first nozzle
opening pressure.
11. If the first nozzle opening pressure is not as specified,
disassemble the nozzle holder and replace the shim
until the pressure is as specified.

CAUTION:
 Use a micrometer to measure shim thickness.

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FUEL SYSTEM 6C – 31
 First nozzle opening pressure adjusting shims
Parts No. (ISUZU) Thickness (mm)
115349-0420 0.40
115349-0430 0.50
115349-0440 0.52
115349-0450 0.54
115349-0460 0.56
115349-0470 0.58
115349-0480 0.60


115349-0490 0.70


Full needle valve lift confirmation
1. Install the gasket and plug on the adjustment retaining
nut.
Gasket: 026508-1140 (Bosch AS)
894227-6020 (ISUZU)
Plug: 157892-1600 (Bosch AS)



2. Position the nozzle holder with the nozzle facing down
and install the dial gauge holder on the nozzle holder.
Dial gauge holder: 157892-5000 (Bosch AS)



3. Install the nut on the dial gauge holder.
Nut: 157892-1000 (Bosch AS)


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FUEL SYSTEM 6C – 33


8. Operate the nozzle tester and increase the in-line
pressure to 34.3 - 44.1 MPa (350 - 450 kg/cm2) 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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6C – 34 FUEL SYSTEM


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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FUEL SYSTEM 6C – 35

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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