Section 13.3 Faulty Overflow Valve

Section 13.3
Faulty Overflow Valve

To determine if a faulty overflow valve is causing a lack of power, perform the following steps:‪

  1. Run Fuel system Test #1: Downstream Pressure Test. Refer to "3.2 Test #1 Downstream Pressure Test" .
  2. If Test #1 indicates faulty overflow valve, proceed to step 3.
  3. Run fuel system Test #3: Flow Test – At Fuel Filter. Refer to "3.4 Test #3 Flow Test — At Fuel Filter" .
  4. If the overflow valve is found to be faulty, replace the overflow valve. Refer to "13.3.1 Overflow Valve Replacement" .

Section 13.3.1
Overflow Valve Replacement

Perform the following steps to replace the overflow valve.‪

  1. Remove the overflow valve from the fuel return line.
  2. Install a new overflow valve. Tighten the valve to 48-52 N·m (35-38 lb·ft). See Figure "Overflow Valve Location" .
    Click to see this graphic in a separate window

     1. Unit Pump‪

     4. Overflow Valve‪

     2. Bypass to Fuel Return Port‪

     5. Constant Ventilation (overflow)‪

     3. Fuel Injector‪

    Figure 1. Overflow Valve Location

  3. Verify overflow valve replacement; refer to "13.3.1.1 Test the Engine with Replaced Overflow Valve" .
Section 13.3.1.1
Test the Engine with Replaced Overflow Valve

Perform the following steps to determine if the replaced overflow valve has resolved lack of power condition:‪

warning

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 and run the engine.
  2. Run the engine at idle with a no-load condition for approximately five minutes, allowing the engine coolant to reach normal operating range.
  3. Test drive the vehicle to ensure lack of power has been resolved.
    1. If no lack of power occurred during the test drive, no further troubleshooting is required. Shut down the engine.
    2. If lack of power occurred during the test drive, shut down the engine. Check for high fuel temperature return; refer to "13.4 High Fuel Temperature Return" .


EPA07 MBE 900 DDEC VI Troubleshooting Guide - 6SE580
Generated on 10-13-2008

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