Hummer H1 (2006+). Manual - part 168

3-14 Fuel, Emissions, and Exhaust

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Figure 3-6:    Fuel Injection Pump 

Removal

1.

Disconnect the negative battery cable.

2.

Drain the cooling system.

3.

Remove the air cleaner assembly and the air intake pipe.

4.

Remove the interior engine cover (Refer to section 10).

5.

Remove the drive belt.

NOTE:

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

6.

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

7.

Remove the fuel rail inlet pipe from the injection pump and the fuel rail (Figure 3-13).

8.

Remove the thermostat housing crossover (Refer to section 4).

9.

Remove the center and right intake manifolds (Refer to section 2).

10. Remove the turbocharger (Refer to section 2).

11. Unplug the fuel pressure regulator wire connector.

12. Loosen the fuel supply and return line clamps and remove the hoses from the pump.

13. Remove the four pump bolts and the fuel pump from the block (Figure 3-7).

Service

The injection pump is not serviceable.The pump should be replaced as an assembly if an internal fault occurs.

Installation

1.

Install the fuel pump and torque the four retaining bolts to 15 lb-ft. (20 N·m).

2.

Install the fuel supply and return hoses, tighten the clamps.

3.

Install the turbocharger.

4.

Install the center and right intake manifolds.

5.

Install the thermostat housing crossover.

DRIVE GEAR

HIGH PRESSURE

OUTLET

SUCTION

INLET

FUEL

RETURN

FUEL PRESSURE

REGULATOR

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 Fuel, Emissions, and Exhaust  3-15

6.

Install the fuel rail inlet pipe and tighten to 30 lb-ft. (41 N·m).

7.

Install the A/C compressor, tighten the bolts to 37 lb-ft. (50 N·m).

8.

Install the drive belt.

9.

Install the interior engine cover.

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

11. Fill and bleed the cooling system (Refer to section 4)

12. Connect the negative battery cable.

13. Prime and bleed the fuel system (Refer to section 3).

14. Start the engine and inspect for fuel leaks.

Figure 3-7:   Injection Pump Removal/Installation

Fuel Pressure Regulator

The fuel pressure regulator controls the amount of fuel available for the high-pressure pump.The normally open regulator is pulse-
width modulated against spring force. It operates between 5 and 95 percent duty cycle. The higher the duty cycle the lower the
output pressure. It is commanded by the ECM. When the ignition is turned off the ECM commands the pressure regulator closed
for several seconds.

Diagnosis

The Fuel Pressure Regulator graphing procedure offers valuable information on regulator performance by comparing desired and
actual fuel rail pressure. An almost perfect comparison between actual rail pressure and desired rail pressure is found on a fairly
new, low mileage engine (Figure 3-8). A minor ripple is acceptable behavior for the fuel rail pressure regulator and is seen on high
mileage engines (Figure 3-9). A "shark tooth" fluctuation in actual fuel rail pressure indicates a sticking pressure regulator
(Figure 3-10).

1.

Set up the following Min/Max ranges for graphing the fuel rail pressure on the scan tool.

        - Engine Speed Min/Max range is 0-1,000 RPM. 

        - Actual Fuel Rail Pressure Min/Max range is 1-160 MPa. 

        - Desired Fuel Rail Pressure Min/Max is 1-160 MPa. 

2.

Start and idle the engine.

FUEL

INJECTION

PUMP

TIMING GEAR COVER

3-16 Fuel, Emissions, and Exhaust

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3.

Observe the live plot for sharp changes or shark tooth pattern in the Actual Fuel Rail Pressure while performing the following
actions:

        - Idling the engine 

        - Shifting the transmission from Park to Drive and back to Park 

        - Turning the steering from left stop position to right stop position 

        - Turning the air conditioning ON and OFF 

4.

If there is a violent fluctuation in the Actual Fuel Rail Pressure, as seen in the surging graph (Figure 3-10), replace the fuel
pressure regulator.

Figure 3-8:   Good Zero Miles Fuel Pressure Regulator

3

2

1

(1) Engine Speed
(2) Actual Fuel Rail Pressure
(3) Desired Fuel Rail Pressure

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 Fuel, Emissions, and Exhaust  3-17

Figure 3-9:   Good 26K Miles Fuel Pressure Regulator

Figure 3-10:   Bad Surging Fuel Pressure Regulator

3

2

1

(1) Engine Speed
(2) Actual Fuel Rail Pressure
(3) Desired Fuel Rail Pressure

(1) Engine Speed
(2) Actual Fuel Rail Pressure
(3) Desired Fuel Rail Pressure

3

2

1