Express 2500 V8-6.6L DSL Turbo (2010)
Fuel Pressure: Testing and Inspection
Fuel System Diagnosis
VIN L
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
Fuel is supplied to the fuel injection pump from the fuel tank sending unit, an electric fuel pump draws fuel from the tank and pushes fuel through the
lines to the fuel conditioning module. The fuel conditioning module consists of a fuel filter, water in fuel sensor, fuel filter vacuum switch and a hand
primer. The fuel injection pump has a low pressure pump that draws fuel in from the fuel conditioning module and supplies the high pressure side of the
fuel injection pump, exhaust after treatment fuel injector and the fuel injector return system, with 4 bar (58 psi) of pressure. Excess fuel is returned back
to the fuel tank or the conditioning module. Fuel that is returned to the conditioning module helps to heat the fuel going to the fuel injection pump.
This diagnostic is used to test the low pressure fuel supply to the fuel injection pump.
Diagnostic Aids
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An Engine Cranks but Will Not Run or Hard Start symptom may exist if air is being drawn into the fuel injection system due to the following
conditions:
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Deformed or cut O-rings at the fuel supply line connections
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Improperly seated fuel supply line fittings
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Porous or weathered rubber fuel supply lines
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Fuel filter vent screw not tighten or cross threaded
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Fuel filter not tightened properly
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Contaminated or improper fuel may cause driveability or starting issues. Refer to Fuel System Specifications (See: Specifications/Fuel System
Specifications) and Contaminants-in-Fuel Diagnosis (See: Computers and Control Systems/Testing and Inspection/Component Tests and General
Diagnostics/Contaminants-in-Fuel Diagnosis).
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A leaking fuel injector return line constant pressure regulator may cause No-Start, Hard Start, or Stall conditions.
Reference Information
Description and Operation
Fuel System Description (See: Computers and Control Systems/Description and Operation/Fuel System Description)
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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EN-47969 Fuel Supply Diagnostic Hose
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J 44581 Fuel Line Disconnect Tool
