Avalanche 4WD V8-5.3L (2011)
Fuel Pressure: Testing and Inspection
Fuel System Diagnosis
Fuel System Diagnosis
Diagnostic Instructions
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Perform the Diagnostic System Check - Vehicle See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle prior to using this diagnostic procedure.
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Review Strategy Based Diagnosis See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis for an
overview of the diagnostic approach.
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Diagnostic Procedure Instructions See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure Instructions
provides an overview of each diagnostic category.
Circuit/System Description
When the ignition is turned ON, the engine control module (ECM) supplies power to the in-tank fuel pump, by energizing the fuel pump relay. The
in-tank fuel pump remains ON as long as the engine is cranking or running and the ECM receives crankshaft reference pulses. If there are no reference
pulses, the ECM turns the in-tank fuel pump OFF, 2 seconds after the ignition switch is turned ON or 2 seconds after the engine stops running. The
electric fuel pump is incorporated into the modular fuel pump and sender assembly and is located inside the fuel tank. The fuel pump supplies fuel
through a fuel filter, also located in the modular fuel pump and sender assembly, through the fuel feed pipes, to the fuel rail assembly. The fuel pump
provides fuel at a pressure above the pressure needed by the fuel injectors. The fuel pressure regulator, located in the modular fuel pump and sender
assembly, keeps the fuel available to the fuel injectors at a regulated pressure. When the fuel pressure rises above the pressure regulator calibration, the
pressure is relieved, with excess fuel exhausted into the modular fuel pump and sender assembly reservoir.
Electrical Information Reference
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Circuit Testing See: Testing and Inspection/Component Tests and General Diagnostics/Circuit Testing/Circuit Testing
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Connector Repairs See: Testing and Inspection/Component Tests and General Diagnostics/Connector Repairs/Connector Repairs
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Testing for Intermittent Conditions and Poor Connections See: Testing and Inspection/Component Tests and General Diagnostics/Circuit
Testing/Testing for Intermittent Conditions and Poor Connections
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Wiring Repairs See: Testing and Inspection/Component Tests and General Diagnostics/Wiring Repairs/Wiring Repairs
Scan Tool Reference
Control Module References See: Testing and Inspection/Programming and Relearningfor scan tool information
Special Tools
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CH-48027 Digital Fuel Pressure Gauge
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J 37287 Fuel Line Shut-Off Adapters
Circuit/System Verification
Note:
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Inspect the fuel system for damage or external leaks before proceeding.
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Verify that adequate fuel is in the fuel tank before proceeding.
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The fuel pump relay may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.
1. Ignition ON, command the Fuel Pump Relay ON with a scan tool. You should hear the fuel pump turn ON and OFF.
‹› If the fuel pump does not operate, refer to Fuel Pump Electrical Circuit Diagnosis See: Computers and Control Systems/Testing and
Inspection/Component Tests and General Diagnostics/Fuel Pump Electrical Circuit Diagnosis.
2. Ignition OFF, all accessories OFF, install the CH-48027 . Refer to Fuel Pressure Gauge Installation and Removal See: Fuel Pressure Gauge
Installation and Removal.
3. Ignition ON, command the Fuel Pump Relay ON with a scan tool. Verify the fuel pressure is between 345-414 kPa (50-60 psi) and remains steady
for 5 minutes.
Circuit/System Testing
Note:
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The fuel pump relay may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.
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DO NOT start the engine.
1. Ignition ON, command the Fuel Pump Relay ON with a scan tool and observe the fuel pressure gauge while the fuel pump is operating. Verify the
