Hummer H1 (2006+). Manual - part 167

3-10 Fuel, Emissions, and Exhaust

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Figure 3-3:   Mass Air Flow Sensor Replacement

Installation

1.

Install the sensor in the air intake hose and secure with the two screws.

2.

Connect the electrical connector. 

Fuel Manager (Filter-Water Separator)

The fuel manager is located on the driver side of the engine compartment on the vertical portion of the cowl panel (Figure 3-4). It
performs five functions which are:

• Fuel filtering (2-stage)

• Water separation

• Water detection

• Water drain

• Fuel heater

Fuel filtering and water separation is achieved through a 2-stage, replaceable, filter element. The first stage of the filter is used to remove
debris from the fuel and the second stage causes water to separate from the fuel in the form of droplets. These droplets are collected in a
reservoir at the bottom of the filter element housing. Water can be drained off through a drain valve and hose, located in the driver side
wheel well.

Water detection and fuel heating are controlled by sensors in the filter housing. Water build-up causes the water in fuel (WIF) sensor to
activate the instrument panel “drain filter” light. Fuel heating occurs during cold ambient temperatures. It is controlled by a temperature
sensitive switch that is internal to the heater. When temperature falls to a point where wax build-up could occur, the switch activates the
heat element within the filter housing.

MASS AIR

FLOW SENSOR

AIR CLEANER

ASSEMBLY

ELECTRICAL

CONNECTOR

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 Fuel, Emissions, and Exhaust  3-11

Figure 3-4:   Fuel Manager Breakdown

FILTER

SEAL

FUEL

WATER IN

ELEMENT

FUEL

SENSOR

HEATER

INLET

OUTLET

HAND

PRIME

PUMP

WATER

LOWER

BOWL

ASSEMBLY

DRAIN

VALVE

FUEL FILTER

INLET HOUSING

3-12 Fuel, Emissions, and Exhaust

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Fuel Filter Replacement

Removal

1.

Drain the fuel from the fuel manager (Figure 3-4).

2.

Loosen the fuel hose clamps.

3.

Disconnect the manager inlet and outlet hoses from the housing.

4.

Disconnect the fuel manager electrical connectors.

5.

Remove the fuel managers nuts and lock washers.

6.

Remove the fuel manager assembly.

7.

Remove the fuel filter from the lower bowl assembly and from the fuel filter inlet housing.

Installation

1.

Install the fuel filter to the fuel filter inlet housing and install the lower bowl assembly.

2.

Place the fuel manager assembly on the bracket. 

3.

Install the fuel manager nuts and lock washers and tighten the nuts to 15 lb-ft. (20 N·m).

4.

Connect the fuel manager electrical connectors.

5.

Install the fuel hoses.

6.

Position the fuel hose clamps on the hoses and tighten.

7.

Purge the air from the fuel manager.

8.

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

9.

Once the engine starts, inspect for fuel leaks.

Purging Air From Fuel Manager (Priming the Fuel System)

1.

Prior to priming the engine, ensure that the following has been completed

• There is fuel in the fuel tank. 

• The fuel filter has been installed and properly tightened. 

• The fuel lines are properly connected.

2.

Press the fuel priming pump multiple times (it may take as many as forty times) (Figure 3-4). You may feel some resistance in
the pump after you press it a few times.

3.

Try to start the engine. If the engine does not start, begin the priming process again.

4.

Start the engine and allow it to idle for a few minutes.

5.

Check the filter for leaks.

Water In Fuel Sensor (WIF)

For vehicles with an illuminated drain filter light, verify that there is no water present in the fuel manager by draining a cup or two
of fuel from the manager into a clear container (Figure 3-4). If water is present in the fuel, it will settle to the bottom of the
container after sitting for approximately a minute.

• If water is present in the fuel, drain and clean the fuel system and replenish with fresh fuel.

• If water is not present in the fuel, change the water-in-fuel switch located in the bottom of the fuel manager 

• Do not change the fuel manager for a water-in-fuel switch problem.

Fuel Heater

The fuel heater is mounted in the bottom of the fuel manager  (Figures 3-4 and 3-5). The purpose of the heater is to prevent waxing
of the fuel in cold temperatures. The fuel heater is internally switched on and off based on fuel temperature. When fuel temperature
is less then 45˚F the heater will activate, as the fuel temperature warms to around 85˚F the heater will turn off. 

The fuel heater is replaced with the lower bowl assembly.

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 Fuel, Emissions, and Exhaust  3-13

Figure 3-5:   Fuel Manager Schematic

 Injection Pump

The injection pump is gear driven off the cam and is located at the front of the engine valley (Figure 3-6). It has a supply pump
side, a high-pressure pump side, fuel return and a pressure regulator. Timing is not required for this pump.