MBE 4000 DDEC VI Troubleshooting – Section 3.2 Fuel System Troubleshooting Tests

Section 3.2
Fuel System Troubleshooting Tests

To perform fuel troubleshooting tests on the engine:‪

1. Run the engine for two to three minutes at rated speed, 1900 rpm.

   NOTICE:
   Correct torque on the high pressure lines is critical. Incorrect torques could result in leaks or lack of power due to restricted fuel flow.‪

2. Perform a visual inspection of all fuel lines, pressure fittings, and components, including all the fittings that connect the fuel feed and drain hoses to the fuel filter housing. Replace any components found to be damaged or leaking. If necessary, tighten all high-pressure fittings to 36 (27 lb·ft) and thrust bolts to 45 N·m (33 lb·ft).

   Note: If the high pressure fuel lines are leaking, do not tighten. Replace the high pressure fuel lines.

3. Inspect the primary filter (frame mounted) element. Replace if necessary.
4. Inspect the filter element in the main fuel filter. Replace if necessary.
5. Continue to run the engine until it reaches the operating temperature of approximately 82°C (180°F). When the operating temperature has been reached, shut the engine down and go to the next step.

   Note: When doing these tests, be sure the temperature of the fuel in the fuel tank is no higher than 40°C (104°F). Collect any fuel which flows out during the test. The fuel should flow through free of bubbles.

6. Perform the fuel system troubleshooting tests and correct any problems. As indicated by the test results, perform any follow-up tests or check troubleshooting tables, as required. Make the necessary repairs and/or replacements. For troubleshooting tests and tables see the following subjects:
   1. Test #1: Downstream Pressure Test, refer to "3.3 Test #1 Downstream Pressure Test" .
   2. Test #2: Flow Test-At Fuel Injector, refer to "3.4 Test #2 Fuel Pressure Test At the Fuel Filter" .
   3. Test #3: Flow Test-At Fuel Filter, refer to "3.5 Test #3 Flow Test — At Fuel Filter" .
   4. Test #4: Upstream Pressure Test, refer to "3.5 Test #4 Upstream Pressure Test" .
   5. Test #5: Leak Test,
      refer to "3.7 Test #5 Leak Test" .
7. When all the tests are completed, the test equipment removed, and all repairs/replacements have been made, prime the fuel system.
   1. Pump the secondary fuel filter hand pump until resistance is felt.

      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.‪

   2. Crank the engine for 30 seconds at a time, but no longer . Before cranking the engine again, wait at least two minutes and pump the secondary fuel filter hand pump again until resistance is felt. The engine should start within four 30-second attempts.
8. If the problem has still not been resolved, test vehicle performance on a chassis dynamometer. If there is no improvement in fuel consumption or performance, connect a fuel consumption measuring system.