Silverado 1500 4WD V8-6.0L (2010)
Fuel Pressure: Testing and Inspection
Fuel System Diagnosis (FPCM)
Fuel System Diagnosis (FPCM)
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
The engine control module (ECM) supplies voltage to the fuel pump control module (FPCM) when the ECM detects that the ignition is ON. The voltage
from the ECM to the FPCM remains active for 2 seconds, unless the engine is in Crank or Run. While this voltage is being received, the FPCM closes
the ground switch of the fuel pump and also supplies a varying voltage to the fuel tank pump module in order to maintain the desired fuel rail pressure.
The fuel system is an electronic returnless on-demand design. A returnless fuel system reduces the internal temperature of the fuel tank by not returning
hot fuel from the engine to the fuel tank. Reducing the internal temperature of the fuel tank results in lower evaporative emissions.
The fuel tank stores the fuel supply. An electric turbine style fuel pump is contained by the fuel pump module inside the fuel tank. The fuel pump
supplies high pressure fuel through the fuel filter and the fuel feed pipe to the fuel injection system. The fuel pump also supplies fuel to a venturi pump
located on the bottom of the fuel pump module. The function of the venturi pump is to fill the fuel pump module reservoir. The fuel pump module
contains a reverse flow check valve. The check valve maintains fuel pressure in the fuel feed pipe and the fuel rail in order to prevent long cranking
times.
Reference Information
Description and Operation
Fuel System Description (See: Computers and Control Systems/Description and Operation/Fuel System Description)
Electrical Information Reference
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Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
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Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Connector
Repairs/Connector Repairs)
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Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/General
Electrical Diagnostic Procedures/Circuit Testing/Testing for Intermittent Conditions and Poor Connections)
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Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Wiring
Repairs/Wiring Repairs)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Special Tools
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CH-48027 Digital Pressure Gauge
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J 37287 Fuel Line Shut-off Adapter
Circuit/System Verification
Note:
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Repair all fuel system related DTCs before performing this diagnostic, unless instructed here from a DTC diagnostic.
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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 may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.
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Before proceeding with this test review the User Manual CH 48027-5 for Safety Information and Instructions.
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DO NOT perform the Fuel System Diagnosis if the engine coolant temperature is above 60°C (150°F). High fuel pressure readings may result due
to hot soak fuel boiling. With the engine OFF, the fuel pressure may increase beyond the pressure relief valves set point of 690 kPa = / -5 % (100
psi ±5 %).
1. Ignition OFF, all accessories OFF, install a CH-48027 . Refer to Fuel Pressure Gauge Installation and Removal (See: Fuel Pressure Gauge
