GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2000 🢒 LeSabre 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 Fuel Injector Balance Test
Table 1: Injector Balance Test Example
Table 2: Test Procedure

Object Number: 17713 Size: SF
(1)First Reading
(2)Second Reading

Injector Balance Test Example

Cylinder

1

2

3

4

5

6

1st Reading

330 kPa (48 psi)

330 kPa (48 psi)

330 kPa (48 psi)

330 kPa (48 psi)

330 kPa (48 psi)

330 kPa (48 psi)

2nd Reading

165 kPa (24 psi)

124 kPa (18 psi)

152 kPa (22 psi)

186 kPa (27 psi)

165 kPa (24 psi)

165 kPa (24 psi)

Amount of Drop

165 kPa (24 psi)

206 kPa (30 psi)

178 kPa (26 psi)

144 kPa (21 psi)

165 kPa (24 psi)

165 kPa (24 psi)

Average Range: 162-183 kPa (23.5-26.5 psi)

Injector OK

Faulty injector - too much fuel drop

Injector OK

Faulty injector - too little fuel drop

Injector OK

Injector OK

Test Description

The numbers below refer to the step numbers on the diagnostic table.

Caution: Wrap a shop towel around the fuel pressure connection in order to reduce the risk of fire and personal injury. The towel will absorb any fuel leakage that occurs during the connection of the fuel pressure gage. Place the towel in an approved container when the connection of the fuel pressure gage is complete.

  1. The fuel pressure should be within the specified range.

    2.

  2. The fuel pressure should reach a steady value.

    3.

  3. If the pressure drop value for each fuel injector is within 10 kPa (1.5 psi) of the average pressure drop value, the fuel injectors are flowing properly. Calculate the pressure drop value for each fuel injector by subtracting the second pressure reading from the first pressure reading. Refer to the Injector Balance Test Example.

Test Procedure

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Did you perform the Fuel Injector Coil Test?

--

Go to Step 3

Go to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F)

3

Important: Do not perform this test if engine coolant temperature is above 94°C (201°F)

With a scan tool, monitor the ECT parameter.

Does the ECT parameter measure less than the specified value

94°C (201°F)

Go to Step 4

--

4

  1. Turn OFF the ignition.

    2. Caution: Wrap a shop towel around the fuel pressure connection in order to reduce the risk of fire and personal injury. The towel will absorb any fuel leakage that occurs during the connection of the fuel pressure gage. Place the towel in an approved container when the connection of the fuel pressure gage is complete.

  2. Install the J 34730-1A Fuel Pressure Gauge.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, Command the fuel pump ON.
  5. Place the bleed hose of the fuel pressure gauge into an approved gasoline container.
  6. Bleed the air out of the fuel pressure gauge.

    7. Important: The fuel pump will run for approximately 2 seconds. Repeat Step 7 as necessary in order to achieve the highest possible fuel pressure.

  7. Use the scan tool to command the fuel pump ON.
  8. Use the fuel pressure gauge to observe the fuel pressure parameter.

Does the fuel pressure measure within the specified value?

333-376 kPa (48-55 psi)

Go to Step 5

Go to Fuel System Pressure Test (VIN K)

5

After the fuel pump stops, the fuel pressure may vary slightly, then should hold steady.

Does the fuel pressure remain constant within the specified value?

333-376 kPa (48-55 psi)

Go to Step 6

Go to Fuel System Pressure Test (VIN K)

6

  1. Install the J 39021 Fuel Injector Coil/Balance Tester.
  2. With the fuel injector tester, select the 0.5-2.5 amp position.
  3. With a scan tool, command the fuel pump ON and then OFF.
  4. After the fuel pressure stabilizes, record the fuel pressure parameter on the fuel pressure gauge . This is the 1st pressure reading.
  5. Press the PUSH TO START TEST button on the fuel injector tester.
  6. When the fuel pressure gauge needle stops moving, record the fuel pressure parameter. This is the 2nd pressure reading.
  7. Repeat each remaining fuel injector.
  8. Subtract the 2nd pressure reading from the 1st pressure reading for each fuel injector. The result is the pressure drop value.
  9. Record a pressure drop value for each fuel injector.
  10. Add all of the individual pressure drop values. This is the total pressure drop.
  11. Divide the total pressure drop by the number of fuel injectors. This is the average pressure drop.

Does any fuel injector have a pressure drop value that is either higher than the average pressure drop or lower than the average pressure drop by the specified value?

10 kPa (1.5 psi)

Go to Step 7

Symptoms

7

Perform the Fuel Injector Cleaning .

Did you complete the procedure?

--

Go to Step 8

--

8

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Symptoms