Hummer H2. Manual — part 1601

subtracting the second pressure reading from the first pressure reading.

Fuel Injector Balance Test with Tech 2

Step

Action

Values

Yes

No

Schematic Reference:Engine Controls Schematics
Connector End View Reference:Engine Controls Connector End Views or Powertrain Control
Module (PCM) Connector End Views

1

Did you perform the Diagnostic System Check -
Engine Controls?

-

Go to Step 2

Go to

Diagnostic

System Check -

Engine

Controls

2

Did you perform the Fuel Injector Coil Test?

-

Go to Step 3

Go to Fuel

Injector Coil

Test

3

1. Turn OFF the ignition.

2. Turn OFF all accessories.

3. Install the fuel pressure gauge. Refer to

Fuel Pressure Gauge Installation and
Removal .

4. Turn ON the ignition, with the engine OFF.

5. Command the fuel pump ON with a scan

tool.

6. Observe the fuel pressure gauge, with the

fuel pump commanded ON.

Is the fuel pressure within the specified value?

IMPORTANT:

Do not perform this test if the engine coolant
temperature (ECT) is above 94°C (201°F).

IMPORTANT:

Verify there is adequate fuel in the fuel tank
before proceeding with this diagnostic.

IMPORTANT:

z

You may need to command the fuel
pump ON a few times in order to
obtain the highest possible fuel
pressure.

z

Do not start the engine.

385-425 kPa

(55-62 psi)

VIN: (V, T,

U) Gasoline

335-375 kPa

(48-54 psi)

VIN: Z

Ethanol

Go to Step 4

Go to Fuel

System

Diagnosis

IMPORTANT:

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls (Troubleshooting) - 4.8L, 5.3L, and 6.0L - Hummer H2

4

Observe the fuel pressure gauge for 1
minute.Does the fuel pressure drop more than the
specified value?

The fuel pressure may vary slightly when the
fuel pump stops operating. After the fuel pump
stops operating, the fuel pressure should
stabilize and remain constant.

34 kPa (5 psi)

Go to Fuel

System

Diagnosis

Go to Step 5

5

1. Select the Fuel Injector Balance Test

function with a scan tool.

2. Select an injector to be tested.

3. Press Enter. This will prime the fuel

system.

4. Record the fuel pressure indicated by the

fuel pressure gauge after the fuel pressure
stabilizes. This is the 1st pressure reading.

5. Energize the fuel injector by depressing the

Pulse Injector button on the scan tool. This
will energize the injector and decrease the
fuel pressure.

6. Record the fuel pressure indicated by the

fuel pressure gauge after the fuel injector
has stopped pulsing. This is the 2nd
pressure reading.

7. Press Enter again to bring you back to the

Select Injector screen.

8. Repeat for each fuel injector.

9. Subtract the 2nd pressure reading from the

1st pressure reading for one fuel injector.
The result is the pressure drop value.

10. Obtain a pressure drop value for each fuel

injector.

NOTE:

Refer to Fuel Injector Balance Test Notice in
Cautions and Notices.

IMPORTANT:

Record the fuel pressure value
immediately after the fuel injector stops
pulsing. The fuel pressure may rise after
the fuel injector stops pulsing. Do not
record the higher fuel pressure value.

10 kPa (1.5

psi)

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls (Troubleshooting) - 4.8L, 5.3L, and 6.0L - Hummer H2

FUEL TANK LEAK TEST

Description

The fuel tank leak test is used to locate any fuel or fuel vapor escaping the fuel tank area. Fuel vapors escaping
above the fuel level will be detected when the evaporative emission (EVAP) diagnostics complete one test
cycle. The malfunction indicator lamp (MIL) will illuminate after the EVAP diagnostics have failed two test
cycles.

Diagnostic Aids

z

Operate the vehicle under the condition of the customers concern. Under high temperature conditions fuel
vapors may increase to the point of EVAP canister vapor saturation. Fuel vapors would then be released
into the atmosphere. Once the engine is running and EVAP purge is enabled, all fuel vapor release would
be eliminated.

z

Movement of the EVAP pipes or fuel pipes may help find an intermittent condition.

z

If the fuel level is low, a leak may not be evident.

Test Description

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

4: This step tests for fuel leaks below the fuel tank fuel level.

5: This step tests for fuel vapors escaping above the fuel level in the fuel tank.

Fuel Tank Leak Test

11. Add all of the individual pressure drop

values. This is the total pressure drop.

12. 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?

Go to Step 6

Go to

Symptoms -

Engine

Controls

6

Perform the Fuel Injector Cleaning Procedure .
Did you complete the procedure?

-

Go to Step 7

-

7

Operate the vehicle in order to verify the repair.
Does a driveability condition still exist?

-

Go to

Symptoms -

Engine

Controls

System OK

Step

Action

Yes

No

Did you perform the Diagnostic System Check - Engine Controls?

Go to

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls (Troubleshooting) - 4.8L, 5.3L, and 6.0L - Hummer H2

1

Go to

Step 2

Diagnostic

System Check

- Engine

Controls

2

1. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in

General Information.

2. Inspect the fuel tank and fuel pipes for damage or external leaks.

Did you find fuel leaking from the fuel tank?

CAUTION:

Gasoline or gasoline vapors are highly flammable. A fire could occur if
an ignition source is present. Never drain or store gasoline or diesel
fuel in an open container, due to the possibility of fire or explosion.
Have a dry chemical (Class B) fire extinguisher nearby.

Go to

Step 6

Go to Step 3

3

1. Turn ON the ignition, with the engine OFF.

2. Command the fuel pump relay ON with a scan tool.

3. Inspect for fuel leaking from the fuel pipes.

Did fuel leak from the fuel pipes?

Go to

Step 7

Go to Step 4

4

1. Turn OFF the ignition.

2. Install the J 41413-200 Evaporative Emissions System Tester

(EEST) and the J 41415-40 Fuel Tank Cap Adaptor or the GE-
41415-50 Interrupted Thread Fuel Tank Cap Adapter.

3. Test for a fuel tank leak referring to the J 41413-210 Operation

Manual.

4. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in

General Information.

5. Inspect for a fuel leak while the system is under pressure.

Did fuel leak from the fuel tank?

IMPORTANT:

If the floating indicator registers any flow after stabilizing, a leak
is evident.

Go to

Step 6

Go to Step 5

1. Using the J 41413-200 and the J 41413-210 Operation Manual,

introduce smoke into the evaporative emission (EVAP) system.

IMPORTANT:

It may be necessary to partially lower the fuel tank. Refer to Fuel
Tank Replacement .

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls (Troubleshooting) - 4.8L, 5.3L, and 6.0L - Hummer H2