MBE 4000 DDEC VI Troubleshooting – Section 4.2 Aerated Fuel

Section 4.2
Aerated Fuel

Check for aerated fuel as follows:‪

1. Disconnect the fuel line return hose from the fitting located at the fuel tank.
2. Place the opened end of fuel line into a suitable container.

   PERSONAL INJURY ‪
   To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked.‪

3. Start the engine.
4. Run the engine at 1000 rpm.
5. Visually check to see if air bubbles are rising to the surface of the fuel within the container.
   1. If air bubbles are present, refer to "4.2.1 Aerated Fuel Repair" .
   2. If air bubbles are not present, shut down the engine. Check for improper valve clearance, and worn or damaged camshaft lobes and roller followers; refer to "4.3 Improper Valve Clearance, Worn or Damaged Camshaft Lobes and Rollers" .

Section 4.2.1
Aerated Fuel Repair

Repair as follows:‪

1. Shut down the engine.
2. Tighten all fuel line connections between fuel tank and fuel pump; refer to OEM guidelines.
3. Visually inspect all fuel lines between fuel tank and fuel pump for leaks.
4. Replace any damaged components.
5. Verify repair of fuel lines:
   1. If no air in the fuel return, refer to "4.2.1.1 Verify Repairs" .
   2. If air in the fuel return, locate and repair. Then refer to "4.2.1.1 Verify Repairs" .

Section 4.2.1.1
Verify Repairs

Verify as follows:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked.‪

1. Start engine.
2. Run the engine at 1000 rpm.
3. Listen for misfiring cylinder.
   1. If the engine is not misfiring, no further troubleshooting is required. Shut down the engine.
   2. If the engine is misfiring, check for improper valve clearance, or worn or damaged camshaft lobes or rollers. Shut down the engine; refer to "4.3 Improper Valve Clearance, Worn or Damaged Camshaft Lobes and Rollers" .