Hummer H2. Manual - part 1599

Gauge Installation and Removal .  

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

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

6. Observe the fuel pressure gauge with the fuel pump 

commanded ON.  

Is the fuel pressure within the specified range?

IMPORTANT:

z

The fuel pump relay may need to be 
commanded ON a few times in order to obtain 
the highest possible fuel pressure.  

z

DO NOT start the engine.  

335-375 

kPa (48-

54 psi)

Go to 

Step 4

Go to Step 8

4

Monitor the fuel pressure gauge for 1 minute.Does the fuel 
pressure decrease by more than the specified value?

IMPORTANT:

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 

Step 7

Go to Step 5

5

1. Relieve the fuel pressure to the first specified value.  

2. Monitor the fuel pressure gauge for 5 minutes.  

Does the fuel pressure decrease by more than the second 
specified value?

69 kPa 

(10 psi)

14 kPa (2 

psi)

Go to 

Step 12

Go to Step 6

6

1. Operate the vehicle within the conditions to reproduce 

the original symptoms.  

2. Monitor the O2 and the Fuel Trim parameters with a 

scan tool.  

Does the scan tool parameters indicate a lean condition?

-

Go to 

Step 9

Go to 

Symptoms - 

Engine 

Controls

7

1. Turn OFF the ignition.  

2. Relieve the fuel pressure. Refer to Fuel Pressure Relief 

Procedure .  

3. Disconnect the chassis fuel hose from the engine 

compartment fuel pipe. Refer to Quick Connect Fitting
(s) Service (Metal Collar) .  

4. Install the J 37287 Fuel Line Shut-off Adapter between 

the chassis fuel hose and the engine compartment fuel 
pipe.  

5. Open the valve on the fuel pipe shut-off adapter.  

-

 

2004 Hummer H2 

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

  

FUEL INJECTOR COIL TEST 

Circuit Description 

The control module enables the appropriate fuel injector pulse for each cylinder. Ignition voltage is supplied 
directly to the fuel injectors. The control module controls each fuel injector by grounding the control circuit via 
a solid state device called a driver. A fuel injector coil winding resistance that is too high or too low will affect 

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

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

8. Bleed the air from the fuel pressure gauge.  

9. Command the fuel pump relay ON and then OFF with a 

scan tool.  

10. Close the fuel feed pipe shut-off valve.  

11. Monitor the fuel pressure gauge for 1 minute.  

Does the fuel pressure remain constant?

Go to 

Step 12 Go to Step 11

8

Is the fuel pressure more than the specified value?

427 kPa 

(62 psi)

VIN Z: 

375 kPa 

(54 psi)

Go to 

Step 12

Go to Step 9

9

Inspect the fuel feed pipe for a restriction. 
Did you find and correct the condition?

-

Go to 

Step 13 Go to Step 10

10

Inspect the harness connectors and the ground circuits of the 
fuel pump for poor connections. Refer to Testing for 
Intermittent Conditions and Poor Connections and 
Connector Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to 

Step 13 Go to Step 12

11

1. Turn OFF the ignition.  

2. Raise the fuel rail, with the fuel lines connected. Refer 

to Fuel Rail Assembly Replacement .  

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

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

5. Replace any leaking fuel injectors. Refer to Fuel 

Injector Replacement .  

Did you complete the replacement?

-

Go to 

Step 13

-

12

Replace the fuel sender. Refer to Fuel Sender Assembly 
Replacement . 
Did you complete the replacement?

-

Go to 

Step 13

-

13

Operate the system in order to verify the repair. 
Did you correct the condition?

-

System 

OK

Go to Step 3

 

2004 Hummer H2 

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

  

engine driveability. A fuel injector control circuit DTC may not set, but a misfire may be apparent. The fuel 
injector coil windings are affected by temperature. The resistance of the fuel injector coil windings will increase 
as the temperature of the fuel injector increases. 

Diagnostic Aids 

z

The use of Dielectric compound GM P/N 12377900 (Canadian P/N 10953529) in the fuel injector 
electrical connector may eliminate a corrosion condition.  

z

Monitoring the misfire current counters, or misfire graph, may help isolate the fuel injector that is causing 
the condition.  

z

Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the 
condition.  

z

Perform the fuel injector coil test within the conditions of the customers concern. A fuel injector 
condition may only be apparent at a certain temperature, or under certain conditions.  

z

If the fuel injector coil test does not isolate the condition perform the fuel injector balance test. Refer to 
Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2 .  

Fuel Injector Coil Test 

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

Observe the ECT sensor parameter with a 
scan tool. 
Is the ECT sensor parameter within the 
specified range?

10-32°C 

(50-90°

F)

Go to Step 3

Go to Step 4

3

Measure the resistance of each fuel injector 
with a DMM. Refer to Testing for 
Continuity in Wiring Systems. 
Do any of the fuel injectors display a 
resistance outside the specified range?

11-14 

ohm

Go to Step 6

Go to Diagnostic 

Aids

4

1. Measure the resistance of each fuel 

injector with a DMM. Refer to 
Testing for Continuity in Wiring 
Systems.  

2. Record each fuel injector value.  

3. Subtract the lowest resistance value 

from the highest resistance value.  

Is the difference equal to, or less than, the 
specified value?

3 ohm

Go to Fuel Injector 

Balance Test with 

Special Tool or Fuel 

Injector Balance Test 

with Tech 2

Go to Step 5

 

2004 Hummer H2 

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

  

FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL 

Description 

The scan tool is first used to energize the fuel pump. The fuel injector tester is then used to pulse each injector 
for a precise amount of time, allowing a measured amount of fuel into the manifold. This causes a drop in 
system fuel pressure that can be recorded and used to compare each injector.

5

1. Add all of the fuel injector resistance 

values, to obtain a total resistance 
value.  

2. Divide the total resistance value by 

the number of fuel injectors, to obtain 
an average resistance value.  

3. Subtract the lowest individual fuel 

injector resistance value from the 
average resistance value.  

4. Compute the difference between the 

highest individual fuel injector 
resistance value and the average 
resistance value.  

5. Replace the fuel injector that displays 

the greatest resistance difference, 
above or below the average. Refer to 
Fuel Injector Replacement .  

Did you complete the replacement?

-

Go to Step 7

-

6

Replace the fuel injector or fuel injectors 
that are out of the specified range. Refer to 
Fuel Injector Replacement . 
Did you complete the replacement?

11-14 

ohm

Go to Step 7

-

7

Operate the system in order to verify the 
repair. 
Did you correct the condition?

-

System OK

Go to Step 2

 

2004 Hummer H2 

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