Note: The hydrometer fuel quality tester provides a general indication of fuel quality and should not be considered scientifically accurate.
1. Drain the fuel filter housing by doing these things:
• Stop the engine.
• Place a container under the drain valve exit hose at the left front side of the engine.
• Open the drain valve.
• Start the engine and operate it at operating speed until clear fuel appears at the drain valve exit hose.
• Fill a 1 -liter (0.946-quart) container with a sample of clean fuel.
• Close the drain valve and stop the engine.
• Bring the fuel sample to 60° F (16° C).
2. Obtain a fuel quality hydrometer (special tool J 34352).
3. Fill the hydrometer with the fuel sample by doing these things:
• Squeeze the hydrometer bulb.
• Submerse the hydrometer tip into the sample.
• Release the bulb, allowing fuel to enter the glass tube until it floats the glass bulb inside the tube.
• Gently spin the hydrometer to relieve the surface tension of the fuel sample.
4. Read the scale on the glass bulb at the point where the top of the fuel sample contacts it (see Figure 7-61):
• If the top of the fuel sample is in the yellow part of the glass bulb scale (above the green part), suspect the presence of gasoline in the fuel.
• If the top of the fuel sample is in the green part of the glass bulb scale, the fuel has high quality (approximate cetane rating of 46 to 50).
• If the top of the fuel sample is in the yellow part of the glass bulb scale (below the green part), the fuel has moderate quality (approximate cetane rating of 41 to 45).
• If the top of the fuel sample is in the red part of the glass bulb scale, the fuel has low quality (approximate cetane rating of 38 to 40).
