Yukon/Denali 4WD V8-4.8L VIN V (2005)
Fuel: Testing and Inspection
With Special Tool
ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS (WITH SPECIAL TOOL)
DESCRIPTION
Water contamination in the fuel system may cause driveability conditions such as hesitation, stalling, no start, or misfires in one or more cylinders.
Water may collect near a single fuel injector at the lowest point in the fuel injection system, and cause a misfire in that cylinder. If the fuel system is
contaminated with water, inspect the fuel system components for rust or deterioration.
Ethanol concentrations of greater than 10 percent in non-blended gasoline, or greater than 85 percent with E85 blended gasoline for flexible fuel
applications, can cause driveability conditions and may contribute to fuel system deterioration. Excessive ethanol concentrations can result in
driveability conditions such as hesitation, lack of power, stalling, or a no start, and may contribute to fuel system corrosion, deterioration of fuel
system components, and a restricted fuel filter.
TEST PROCEDURE
1. Test the fuel composition using J 44175 Fuel Composition Tester and J 44175-3 Instruction Manual.
2. If water appears in the fuel sample, perform the following steps:
1. Clean the fuel system. Refer to Fuel System Cleaning.
2. Replace the fuel filter if the vehicle is equipped with a serviceable fuel filter.
Fuel Composition Test Examples
3. Subtract 50 from the reading on the DMM in order to obtain the percentage of alcohol in the fuel sample. Refer to the examples in the Fuel
Composition Test Examples table.
4. If the non-blended gasoline fuel sample contains more than 15 percent ethanol, or if the E85 blended gasoline fuel sample contains more than 85
percent ethanol, add fresh, regular gasoline to the vehicle's fuel tank.
5. Test the fuel composition.
6. If additional testing indicates that the ethanol percentage is still more above 15 percent for a non-blended gasoline sample, drain and replace the
vehicle's fuel. Refer to Fuel System Cleaning.If additional testing indicates that the E85 blended gasoline sample is still above 85 percent,
continue adding fresh, regular gasoline until the ethanol content is 85 percent or less.
