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For 1990-2009 cars only

SMU - Revised Fuel Leaks Inside of Engine Diagnostic

Subject:Revised Fuel Leaks Inside of Engine Diagnostic

Models:2001-2003 Chevrolet Silverado
2003-2004 Chevrolet Kodiak
2001-2003 GMC Sierra
2003-2004 GMC Topkick
with 6.6L Diesel Engine (VIN 1 - RPO LB7)



This bulletin is being issued to revise the Fuel Leaks Inside of Engine diagnostic in the Engine Controls sub-section of the Service Manual. Please replace the current information in the Service Manual with the following information.

The following information has been updated within SI. If you are using a paper version of this Service Manual, please make a reference to this bulletin on the affected page.

The following step has been added before the first step of the diagnostic to test the ability of the fuel system to create adequate fuel pressure. If the engine has fuel in the engine oil, and the fuel system cannot create full fuel pressure at idle, the problem is in the high-pressure fuel system.

The new step listed below is inserted before the current Step 1.

  1. Test the high pressure fuel system performance.
  2. 1.1. Start and idle the engine.
    1.2. Command the fuel pressure to 160 MPa with a scan tool.
    1.3. Observe the Actual Fuel Rail Pressure parameter with a scan tool.
           - If the Actual Fuel Rail Pressure parameter is within 2 MPa of commanded pressure, continue this diagnostic.
           - If the Actual Fuel Rail Pressure parameter is not within 2 MPa of commanded pressure, go to Fuel System Diagnosis -- High Pressure Side.
  3. (Current Step 1 will now become Step 2).