Isuzu N-Series. Manual - part 524

6C-4   Fuel System

Fuel Supply Pump

Legend

1. Fuel Temperature Sensor
2. Fuel Rail Pressure Regulator
3. High Pressure Piping

4. Camshaft Key
5. Camshaft Nut

 

N6A6359E

Fuel System   6C-5

Fuel Injector

Legend

1. Terminal Stud
2. Fuel Leak-off Port
3. O-ring
4. Fuel Inlet Port
5. Injector Parts Number Marking
6. Fuel Injector ID Plate

 

Fuel Filter

Legend

1. Priming Pump
2. Cartridge
3. Sensor
4. Heater
5. Drain Plug

 

Functional check
Air bleeding

Legend

1. Priming Pump
2. Air Bleed Plug

 

1. Before starting the engine

a. Fit a tray below the fuel filter (below the air

bleed plug).

b. Loosen the plug adequately and operate the

priming pump more than 20 times until the fuel
overflows from the plug hole.

N6A6360E

N6A6361E

N6A6362E

N6A6362E

6C-6   Fuel System

c. Tighten the plug, and operate the priming pump

more than 10 times until it is filled with fuel.
After waiting for approximately a minute, loosen
the plug and bleed off the air in the fuel filter.
(This work must be repeated a minimum of
three times until no more air comes out from the
plug.)

d. Tighten the plug firmly and wipe the fuel in the

surrounding area. Operate the priming pump
(10 to 15 times) till it is filled with fuel and then
send fuel to the engine.

2. After starting the engine

a. Start the engine by rotating the starter without

depressing the accelerator pedal.

b. After starting, maintain the idling rotation for 5

seconds.

c. Slowly rotate the idling control knob clockwise

and maintain it for 3 minutes.

d. Fully depress the accelerator pedal and

increase the rotations to maximum. (Repeat
this operation several times)

e. Rotate the idling knob counterclockwise and

return to idling mode.

Caution:
If the air bleeding work is insufficient then it could lead
to faults in the engine. Therefore, the procedures after
starting the engine should always be implemented.

Water drain
A warning lamp will light up if water is collected more
than fixed quantity in the sedimenter. If the warning
lights up, drain out the water by following operations:

• Fit a tray below the fuel filter.
• Loosen the drain plug.
• Operate the priming pump several times to

discharge the water.

• Tighten the drain plug after discharging the water.
• Operate the priming pump several times and

check for fuel leakage.

• Check that the warning lamp in the meter is off.

Fuel system vacuum check
Use this procedure to measure the vacuum (negative
pressure) discharge side the fuel system.

Important:
The fuel pressure/vacuum gauge assembly (gauge (1))
and the fuel pressure/vacuum gauge adapter (adapter
(5)) must be cleaned before connect to the fuel line.
Otherwise, foreign material adherent to the tools may
damage the fuel supply pump.

1. Disconnect the fuel hose from the fuel filter

housing. (fuel supply pump side).

2. Install the adapter.

Special tool
Fuel Pressure/Vacuum Gauge Set:
5-8840-2844-0
(Fuel pressure/vacuum gauge adapter: 
EN-47667)

3. Connect the gauge (1) with hose to the adapter

(5).

Special tool
Fuel Pressure/Vacuum Gauge Set:
5-8840-2844-0
(Fuel pressure/vacuum gauge assembly: 
J-44638)

Legend

1. Fuel Pressure/Vacuum Gauge Assembly
2. Fuel Pipe (Intake Side)
3. Fuel Pipe (Discharge Side)
4. Fuel Filter
5. Fuel Pressure/Vacuum Gauge Adapter

 

4. Loosen the air bleeding plug on the supply pump.
5. Use your hand to operate the fuel filter priming

pump. Operate the pump until all the air has been
bled from the system.

6. Start the engine and allow it to idle. 

N6A6363E

Fuel System   6C-7

7. Note the gauge (1) reading. If the reading is

normal, go to Step 8. If the fuel vacuum is greater
than the specified value, there is a problem in the
fuel system. Perform the procedures outlined
below.

• Replace the cartridge fuel filter element. 
• Check the fuel delivery pipe. If it is clogged, it

must be replaced.

• Remove the fuel pipe at the fuel filter inlet. Use

high-pressure air forced through the fuel pipe to
clean the fuel system.

Caution:

• Remove the fuel filler cap before applying high-

pressure air.

• Do not perform this procedure if the fuel tank is

nearly full (fuel approaching or flowing into the fuel
filler neck). The forced air will spray fuel from the
fuel filler neck.

8. Remove the gauge (1) and hose from the adapter

(5).

9. Remove the adapter (5).

10. Connect the fuel hose.

11. Use your hand to operate the fuel filter priming

pump. Operate the pump until all the air has been
bled from the system.

12. Start the engine and allow it to idle.
13. Inspect the fuel system for fuel leakage.

A List of Defective Phenomena

• Problems with starting
• Hunting during idling
• Insufficient horsepower
• Maximum engine speed is too low
• Engine does not stop
• Exhaust gas is blue or black.

Special Tool

Standard fuel vacuum: Less than 5 inHg

Illustration

Tool Number / 

Description / Remarks

5-8840-2844-0

Fuel Pressure / Vacuum 

Gauge Set

(J-44638 [Fuel Pressure / 

Vacuum Gauge 

Assembly]

EN-47667 [Suction Side 
Fuel Pressure / Vacuum 

Gauge Adapter])

 5884028440