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To determine if the fuel pump is causing excessive white smoke, perform the following steps: ‪

  1. Insert a piece of wire through the fuel pump flange drain hole; see Figure 21518 .

    Fuel Pump Flange Drain Hole Location

  2. Crank the engine momentarily and feel for wire vibration.
    1. If the wire did not vibrate; refer to Section .
    2. If the wire did vibrate, check for aerated fuel; refer to Section .

Drive Hubs and Coupling Replacement

Perform the following for drive hubs or coupling replacement: ‪

  1. Replace the drive hubs or coupling; refer to Section .
  2. Verify the drive hubs and coupling replacement; refer to Section .
Engine Test with Replaced Drive Hubs or Replaced Coupling

Perform the following to determine if replaced drive hubs and coupling resolved excessive white smoke: ‪

  1. Start and run the engine.
  2. Run the engine at idle with a no-load for approximately 5 minutes, allowing the engine coolant to reach normal operating range.
  3. Visually inspect exhaust for excessive white smoke.
    1. If the engine exhaust emission appears normal, no further troubleshooting is required. Shut the engine down.
    2. If the engine exhaust emission is excessively white, shut the engine down. Check for aerated fuel; refer to Section .