Hummer H1 (2006+). Manual - part 169

3-18 Fuel, Emissions, and Exhaust

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Removal

1.

Disconnect the negative battery cable.

2.

Remove the air cleaner assembly and the air intake pipe.

3.

Remove the drive belt.

NOTE:

Do not discharge the A/C system in the next step.

4.

Unbolt the A/C compressor, reposition the compressor, with the hoses attached, to the right side of the engine.

5.

Disconnect and remove the main engine electrical harness connectors.

6.

Disconnect the barometric pressure (BARO) sensor electrical connector.

7.

Disconnect the engine coolant temperature (ECT) sensor electrical connector.

8.

Remove the water outlet tube.

9.

Disconnect the fuel temperature sensor electrical connector.

10. Disconnect the fuel pressure regulator electrical connector.

11. Clean the fuel pressure regulator and high pressure injection pump thoroughly with solvent.

12.  Using compressed air, thoroughly blow dry the regulator and pump.

13. Remove the 3 fuel pressure regulator screws using a T25 TORX

®

.

14. Remove the fuel pressure regulator.

15. If dirt or debris is found in the bore or seating surfaces of the fuel injection pump, perform the following:

          - Place a clean rag over the bore in order to collect the excess fuel. 

          - Bump the engine over in order to flush any debris out of the regulator bore. 

Installation.

1.

Lubricate and install NEW O-rings onto the regulator. Lubricate the O-rings with clean, NEW engine oil.

2.

Install the fuel pressure regulator. Torque the three T25 TORX

®

 screws to 35 lb-in. (4 N·m). 

3.

Retorque the three T25 TORX

®

 screws to 62 lb-in. (7 N·m).

4.

Connect the fuel pressure regulator electrical connector.

5.

Connect the fuel temperature sensor electrical connector.

6.

Install the water outlet tube.

7.

Connect the ECT sensor electrical connector.

8.

Connect the BARO sensor electrical connector.

9.

Connect the main engine electrical harness connectors.

10. Position the A/C compressor and install the A/C compressor bolts and torque to 37 lb-ft. (50 N·m).

11. Install the drive belt.

12. Install the air cleaner assembly and the air intake pipe.

13. Connect the negative battery cable.

14. Prime the fuel system.

15. Start the engine. If the engine stalls, repeat the above step.

16. Once the engine starts, inspect for fuel leaks and verify fuel pressure regulator is functioning properly.

Fuel Rail Pressure Sensor

The fuel rail pressure sensor is mounted in the center of the right common fuel rail(Figure 3-13). Precise measurement of fuel
pressure is imperative for correct system functioning. It has an operating range limit up to 29,000 psi. If it should fail the ECM sets
a DTC and will use a fixed value to command the fuel rail pressure regulator.

Removal

1.

Disconnect the negative battery cable.

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 Fuel, Emissions, and Exhaust  3-19

2.

Drain the cooling system (Refer to section 4)

3.

Remove the air induction hose (Refer to section 3).

4.

Remove the exhaust gas recirculation (EGR) cooler tube (Refer to section 3).

5.

Disconnect the fuel rail pressure sensor electrical connector.

6.

Prior to removal, clean the fuel pressure sensor and surrounding area thoroughly with solvent.

7.

Using compressed air, thoroughly blow dry the sensor and surrounding area.

8.

Remove the fuel pressure sensor.

Installation

1.

Install the fuel pressure sensor and torque to 52 lb-ft. (70 N·m).

2.

Connect the fuel rail pressure sensor electrical connector.

3.

Install the EGR cooler tube.

4.

Install the air induction hose and torque the clamps to 35 lb in (4 N·m)

5.

Fill and bleed the cooling system.

6.

Connect the negative battery cable.

Fuel Rail Pressure Relief Valve

The fuel rail pressure relief valve is located on the rear of the left fuel rail (Figure 3-13). The valve opens if the pressure exceeds
27,550 psi and cycles to maintain pressure. Bleed off fuel returns to the fuel return system. The fuel rail pressure relief valve should
only be serviced with the left fuel rail as an assembly.

Fuel Temp Sensor

The fuel temp sensor is located in the fuel return line near the left common fuel rail (Figure 3-13). The fuel temp sensor is a
thermistor, which receives a 5-volt reference signal from the ECM. The signal voltage decreases as the temperature increases. Fuel
temperature affects fuel viscosity. The ECM uses this information in relating its commands to the FICM.

Removal

1.

Loosen the charged air cooler inlet duct connector to turbocharger clamp.

2.

Remove the charged air cooler inlet duct connector from the turbocharger.

3.

Disconnect the fuel temperature sensor electrical connector.

4.

Remove the fuel temperature sensor from the fuel return line.

Installation

1.

Install the fuel temperature sensor and torque to 16 lb-ft. (22 N·m).

2.

Connect the fuel temperature sensor electrical connector.

3.

Install the charged air cooler inlet duct connector to the turbocharger and tighten the clamp to 53 lb-in. (6 N·m).

4.

Prime the fuel system.

5.

Start the engine and inspect for fuel leaks.

Fuel Injection Control Module

The FICM is mounted on the right front side of the engine. The FICM commands the injectors on time. It requires 93 volts of DC
and up to 20 amps to open an injector. Once open, 11 to 15 amps holds it open. the ECM commands the FICM. The high voltage
creates heat in the FICM and it is cooled by fuel flowing through the unit’s base.

There are two injection pulses to each injection cycle:

• Pilot injection is used up to 2500 rpm. It is a small pre-combustion fuel supply which increases combustion efficiency and 

reduces noise.

• Normal or main injection immediately follows pilot injection.

3-20 Fuel, Emissions, and Exhaust

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Removal

1.

Remove the air cleaner assembly and the air inlet hose.

2.

Remove the fuel lines from the FICM.

3.

Disconnect the two electrical connectors from the FICM (Figure 3-11).

NOTE:

When performing the next step care must be taken to ensure that you do not drop and misplace lower isolators under

FICM.

4.

Remove the three retaining bolts and isolators, then remove the FICM.

Installation

1.

Install the FICM with the three bolts and isolators, torque to 15 lb-ft. (21N•m).

2.

Connect the two electrical connectors to the FICM.

3.

Install the fuel lines to the FICM and tighten the bolts to 25 lb-ft. (34 N•m).

4.

Install the air cleaner assembly and the air inlet hose.

5.

Start the engine and check for fuel leaks.

Figure 3-11:   FICM Connectors

Fuel Hose or Tube 

Removal

1.

Release the fuel lines with the quick connect fittings (Refer to section 3), or loosen the hose clamps.

2.

Remove any P clamps holding the line to the body or frame.

3.

Remove the fuel line.

Installation

1.

Install the fuel line in the same position as removed (Figure 3-12).

2.

Install P clamps.

3.

Start the engine and check for fuel leaks.

FICM

FICM

CONNECTORS

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 Fuel, Emissions, and Exhaust  3-21

Figure 3-12:   Fuel Supply and Return Hose Routing

RETURN HOSES

RETURN HOSE

SUPPLY HOSE

SUPPLY HOSE

FUEL COOLER

P CLAMPS

P CLAMPS

HOSE CLAMPS