Isuzu KB P190. Manual - part 830

Engine Management – V6 – Diagnostics 

Page 6C1-2–42 

 

6.3 

Fuel Injector Balance Test 

 

To avoid irregular fuel pressure readings, do 
not perform this procedure if the engine 
coolant temperature is greater than 94

°°°° C. 

Fuel Injector Balance Test – With Tech 2 

1 

Check the engine coolant temperature is less than 94

°C. 

2 

Perform the fuel injector coil test and replace any fuel injectors that are not functioning correctly before proceeding. 

Refer to 6.2 

Fuel Injector Coil Test. 

3 

Perform the fuel system pressure check and ensure the fuel system is functioning correctly before proceeding with 
the fuel injector balance test. Refer to 6C Fuel System – V6. 

4 

While the fuel pressure gauge is still connected to the fuel pressure test point, pressurise the fuel system. Refer to 
6C Fuel System – V6. 

5 

When the fuel pressure reading stabilises, record the fuel pressure reading indicated by the fuel pressure gauge. 

N O T E  

The fuel pressure reading taken in Step 5 is 
known as the first pressure reading. 

6 

Connect Tech 2 to the data link connector (DLC) and turn the ignition on. 

7 

On Tech 2 select Engine / V6 Engine / Actuator Test / Fuel Injector Balance. 

8 

Follow the Tech 2 prompts, recording the fuel pressure gauge reading for each injector. 

N O T E  

The fuel pressure readings taken in Step 8 are 
known as the second pressure reading 

9 

Perform the Fuel Injector Pressure Drop Calculation in this Section. 

Fuel Injector Balance Test – Without Tech 2 

1 

Check the engine coolant temperature is less than 94

°C. 

2 

Perform the fuel injector coil test and replace any fuel injectors that are not functioning correctly before proceeding. 

Refer to 6.2  Fuel Injector Coil Test. 

3 

Perform the fuel system pressure check and ensure the fuel system is functioning correctly before proceeding with 
the fuel injector balance test. Refer to 6C Fuel System – V6. 

4 

While the fuel pressure gauge is still connected to the fuel pressure test point, pressurise the fuel system. Refer to 
6C Fuel System – V6. 

5 

When the fuel pressure reading stabilises, record the fuel pressure reading indicated by the fuel pressure gauge. 

N O T E  

The fuel pressure reading taken in Step 5 is 
known as the first pressure reading. 

Engine Management – V6 – Diagnostics 

Page 6C1-2–43 

 

6 

Remove the upper intake manifold assembly, refer to 6A1 Engine Mechanical – V6. 

N O T E  

After removing the upper intake manifold, plug 
the lower manifold opening to prevent dirt and 
other contaminants from entering. 

7 

Connect Tool No. J 39021 Fuel Injector Tester (1), and Tool No. J 44602 (3) to the fuel injector connector. Refer to 
Figure 6C1-2 – 14. 

 

Figure 6C1-2 – 14 

Legend 

1 

Fuel Injector Tester – Special Tool J39021 

2 

Fuel Pressure Gauge – Special Tool SD28018 

3 

Fuel Injector Harness Adapter – Special Tool J44602 

4 

To Battery Positive Terminal 

5 Battery 

Earth 

6 

First Pressure Reading 

7 

Second Pressure Reading 

8 

Connect the fuel injector tester battery positive lead (4) and battery negative lead (5) to the battery, refer to Figure 
6C1-2 – 14. 

9 

Set the amperage supply selector of the fuel injector tester to the Balance Test 0.5 – 2.5 A position. 

 

As the fuel pressure tends to increase after 
the fuel injector stops fuel delivery, record the 
fuel pressure value immediately after the fuel 
injector stops fuel delivery. Do not record the 
higher fuel pressure value. 

10 

Press the Push to Start Test Button on the fuel injector tester to activate the fuel injector. 

11 

Record the fuel pressure reading indicated by the fuel pressure gauge. 

N O T E  

The fuel pressure readings taken in Step 10 is 
known as the second pressure reading 

12 

Repeat the balance test pressure reading for each fuel injector. 

13 

Perform the Fuel Injector Pressure Drop Calculation in this Section. 

Engine Management – V6 – Diagnostics 

Page 6C1-2–44 

 

Fuel Injector Pressure Drop Calculation 

Fuel Injector Balance Test Example – Typical Values Shown 

Cylinder 1 

2 

3 

4 

5 

6 

1st Pressure Reading 

360 kPa 

360 kPa 

360 kPa 

360 kPa 

360 kPa 

360 kPa

2nd Pressure 
Reading 

155 kPa 

131 kPa 

155 kPa 

200 kPa 

146 kPa 

150 kPa

Amount of Pressure 
Drop 

205 kPa 

229 kPa 

205 kPa 

160 kPa 

214 kPa 

210 kPa

Average Range 
194 - 214 kPa 

Injector 

OK 

Replace fuel 

injector – too much 

pressure drop 

Injector 

OK 

Replace fuel 

injector – too little 

pressure drop 

Injector 

OK 

Injector 

OK 

Figure 6C1-2 – 15 

1 

Subtract the second pressure reading from the first pressure reading to calculate the pressure drop value. Refer to 
the table in Figure 6C1-2 – 15, typical results. 

2 

Calculate the pressure drop value for each fuel injector. 

3 

Add all the individual pressure drop values of each fuel injector to calculate the total pressure drop. 

4 

Divide the total pressure drop by the number of fuel injectors to calculate the average pressure drop. 

Fuel Injector Pressure Drop Analysis 

1 

A fuel injector is faulty if its pressure drop value deviates from the average pressure drop by more than 10 kPa. 

 

Do not repeat any portion of the test before 
running the engine to prevent the engine from 
flooding. 

2 

Re-test any fuel injector that does not meet the specification. 

3 

Replace all faulty fuel injectors, refer to 2.13 Fuel Rail Assembly, in 6C1-3 Engine Management – V6 – Service 
Operations. 

6.4 

Fuel Injector Leak Down Test 

1 

Turn the ignition switch OFF. 

N O T E  

After removing the upper intake manifold, plug 
the lower manifold opening to prevent dirt and 
other contaminants from entering. 

2 

Remove the upper intake manifold assembly, refer to 6A1 Engine Mechanical – V6. 

Engine Management – V6 – Diagnostics 

Page 6C1-2–45 

 

 

Clean around the area where the fuel 
injectors enter the lower intake manifold. 

3 

Remove the bolt (1), three places, attaching the fuel 
rail to the lower intake manifold. 

 

Care must be taken when removing the fuel 
rail and injector assembly to prevent damage 
to the injector spray tips and injector harness 
connector terminals. 

Support the fuel rail and injector assembly 
after removal. 

4 

Lift up and support the fuel rail and injector assembly.

N O T E  

Do not disconnect the fuel feed hose from the 
fuel rail. 

Figure 6C1-2 – 16 

5 

Place a board (1) with a sheet of clean paper (2), 
preferably white, onto the lower intake manifold. 

6 

Using Tech 2, enable the fuel pump to pressurise the 
fuel system. 

7 

Whilst the fuel system is pressurised, check the 
following: 

• 

Signs of fuel stains on the paper (3). 

• 

Signs of weeping at the fuel injector spray 
tips (4). 

8 

If any of the above conditions are present, replace the 
leaking fuel injector/s, refer to 2.13 Fuel Rail 
Assembly, in 6C1-3 Engine Management – V6 – 
Service Operations.  

9 

Carefully reinstall the fuel rail and injector assembly. 

Figure 6C1-2 – 17 

 

Ensure the fuel injectors are correctly seated 
in the lower intake manifold, and the fuel rail 
attaching brackets are correctly located prior 
to tightening the attaching bolts. 

10 

Tighten the fuel rail bolts to the correct torque specification. 

Fuel rail attaching bolt 
torque specification ..................................8.0 – 12.0 Nm 

11 

Reinstall the upper intake manifold assembly, refer to 6A1 Engine Mechanical – V6. 

12 

Inspect the fuel rail and quick connect fitting for leaks, refer to 6C Fuel System – V6. 

13 

Road test the vehicle and check for correct operation.