Diagnostic Procedures
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Turn engine off. Place container on bottom of fuel filter. Open drain valve and drain fuel filter housing. Fill a 0.95 quart (1 liter) container with a sample of fuel. Close drain valve.
- Obtain a Diesel Fuel Quality Tester (J-38641-B).
- Fill hydrometer with fuel sample by squeezing hydrometer bulb. Submerse hydrometer tip into sample. Release the bulb, allowing fuel to enter glass tube until fuel completely floats glass bulb inside the tube. Gently spin hydrometer to relieve the surface tension of fuel sample. Read the scale on glass bulb at the point where the top of the fuel sample contacts the scale. By reading this value, the value will give an approximate fuel oil specific gravity. Refer to tool instructions on how to determine API Gravity.
- If correct fuel is being used and meets diesel No. 1 or No. 2- fuel oil specific gravity requirements, fuel is okay. If not, fuel should be replaced.