Section 3.5 Test #3 Flow Test — At Fuel Filter

Section 3.5
Test #3 Flow Test — At Fuel Filter

Perform the following test set-up and test to determine the flow at the fuel filter.‪

Section 3.5.1
Test #3 Set-Up

For set-up components see Figure "Test Setup #3 Flow Test at Fuel Filter" .‪

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 1. Clean Container‪

 6. Washers‪

 2. Hose‪

 7. Banjo Fitting and Hose from kit J-46377-A‪

 3. Main Filter Housing‪

 8. Cap from kit J-46377-A‪

 4. Assembly Valve Adaptor from kit J-46377-A‪

 9. Overflow Valve‪

 5. Banjo Bolt‪

10. Original Overflow Return Hose‪

Figure 1. Test Setup #3 Flow Test at Fuel Filter

  1. Disconnect the fuel return line at the overflow valve. When loosening the banjo bolt, hold a second wrench on the overflow valve to avoid loosening the valve.
  2. Using a banjo bolt, nut, and washer from the fuel adaptor parts kit (J-46377-A) , seal off the fuel return line.
  3. In place of the fuel return line, attach the hose with a banjo fitting from the fuel adaptor parts kit (J-46377) to the overflow valve. When tightening the union, hold a second wrench on the overflow valve to avoid over-tightening the valve.
  4. At the main fuel filter, detach the fuel drain line and its fitting from the main filter housing.
  5. In place of the fuel drain line, attach a union from the fuel adaptor parts kit to the main filter housing.
  6. At the union, attach a hose and run the other end of the hose into another clean container.

Section 3.5.2
Test #3

Perform the following:‪

  1. Open the fuel fill cap to release pressure in the fuel tank.
    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.‪

  2. Start the engine and run it at a slow idle, 600 to 650 rpm, until the fuel flows into the container with little or no bubbling.
  3. Check the fuel flow at the fuel filter.

    Note: When beginning the timed portion of this test, take the transparent hose out of the clean container and insert it into a calibrated container or measuring cup.

    1. Measure the quantity of fuel that flows out of the hose in one minute (60 seconds). If more than 2.5 L (84.5 oz.) flow out, fuel flow at the filter is too high (at idle).
    2. Increase the engine speed to 1900 rpm.
    3. Measure the quantity of fuel that flows out of the hose in one minute. If more than 10 L (2.6 gal.) flow out, fuel flow at the filter is too high (at rated speed).
    4. Note: If fuel flow on either test is too high, correct the problem. Fuel flow is OK if the system passes both tests.

  4. Check the fuel flow at the overflow valve.
    1. Reduce engine speed back to slow idle, 600 to 650 rpm.

      Note: When beginning the timed portion of this test, take the transparent hose out of the clean container and insert it into a large calibrated container.

    2. Measure the quantity of fuel that flows out of the hose in one minute (60 seconds).
    3. If more than 10.0 L (2.6 gal.) flows out, overflow valve fuel flow is too high.
    4. If less than 2.5 L (84.5 oz.) flows out, overflow valve fuel flow is too low.
    5. If between 2.5 L (84.5 oz.) and 10.0 Liter (2.6 gal.) flows out, overflow valve fuel flow is within range.
    6. Increase the engine speed to 1900 rpm.
    7. Measure the quantity of fuel that flows out of the hose in one minute (60 seconds).
    8. If more than 10.0 L (2.6 gal.) flows out, overflow valve fuel flow is too high.
    9. If less than 2.5 L (84.5 oz.) flows out, overflow valve fuel flow is too low.
    10. If between 2.5 L (84.5 oz.) and 10.0 Liter (2.6 gal.) flows out, overflow valve fuel flow is within range.
  5. If overflow valve fuel flow is OK and no fuel flows out at the filter, the continuous ventilation port in the fuel filter is blocked by impurities. Open the fuel filter and clean or replace the blocked port.
    • If overflow valve fuel flow is too low and filter fuel flow is too high, see the causes listed in Table "Problem — Fuel Flow Quantity is Too Low at the Overflow Valve and Too High at the Filter" , “Problem-Fuel Flow Quantity is Too Low at the Overflow Valve and Too High at the Filter,” see possible causes listed in Table "Problem — Fuel Flow Quantity is Too Low at the Overflow Valve and Too High at the Filter" and correct the problem. Make any necessary repairs and/or replacements.
    • If overflow valve fuel flow is OK and fuel flow is also OK at the filter, the overflow valve is faulty, leaking, jammed open, worn, or incorrectly installed. Replace the overflow valve, refer to MBE 4000 Service Manual (6SE420), Chapter 2, “Fuel System-Fuel Overflow Valve”.
    • If overflow valve fuel flow is too low and fuel flow is OK at the filter, see the causes listed in Table "Problem — Fuel Flow Quantity is Too Low at the Overflow Valve and Within Range at the Filter" , “Problem-Fuel Flow Quantity is Too Low at the Overflow Valve and Within Range at the Filter,” and correct the problem. Make any necessary repairs and/or replacements.
    • If overflow valve fuel flow is too low and fuel flow is also too low at the filter, perform test #4: Upstream Pressure Test. Refer to "3.5 Test #4 Upstream Pressure Test" .
    • Note: Do not attempt to disassemble the overflow valve. The overflow valve cannot be repaired.

      Problem — Fuel Flow Quantity is Too Low at the Overflow Valve and Too High at the Filter

      Possible Cause

      Remedy

      The main fuel filter is leaking.‪

      Repair or replace the leaking main fuel filter.‪

      The O-ring in the main fuel filter is worn, missing, or incorrectly installed.‪

      Replace the O-ring, or install it correctly.‪

      The main fuel filter cap is loose.‪

      Tighten the to cap 25 N·m (18 lb·ft).‪

      At one or more of the fuel injectors, the transfer tube is leaking, cracked, or incorrectly installed.‪

      Replace the transfer tube(s), or install it correctly.‪

      One or more fuel injectorsare leaking, or cracked.‪

      Replace the fuel injector(s).‪

      Table 3. Problem — Fuel Flow Quantity is Too Low at the Overflow Valve and Too High at the Filter

      Problem — Fuel Flow Quantity is Too Low at the Overflow Valve and Within Range at the Filter

      Possible Cause

      Remedy

      The filter element in the fuel pre-filter is blocked.‪

      Replace the filter element.‪

      The filter element in the main fuel filter is blocked or contaminated.‪

      Clean the inside of the main fuel filter housing. Replace the filter element.‪

      The fuel feed lines are kinked or blocked.‪

      Inspect the lines, fittings, and check valve for blockage. Repair any kinks and replace the lines.‪

      The suction pipe or the strainer at the fuel level is blocked, or touching the bottom of the fuel tank.‪

      Open the fuel fill cap. Inspect the suction pipe and strainer. Remove any blockages, and reposition the suction pipe, if necessary. Remove the fuel level sensor and replace it if necessary.‪

      The check valve in the fuel feed line is blocked or is not sufficiently open (the opening flange is bent at the fitting).‪

      Repair/replace as necessary.‪

      The overflow valve is faulty, or the incorrect valve has been installed. The valve jams when closed as a result of wear or impurities in the fuel.‪

      Inspect the overflow valve. Replace as necessary.‪

      NOTE: Do not attempt to disassemble the overflow valve. The overflow valve cannot be repaired.‪

      Table 4. Problem — Fuel Flow Quantity is Too Low at the Overflow Valve and Within Range at the Filter
  6. Remove the union, transparent hose, banjo bolt, and nut. Restore the fuel return and drain lines to the original installation, as removed.
  7. Make sure the fuel fill cap is tightly closed and the vehicle has been restored to operating condition.

    Problem — Fuel Flow Quantity is Too Low at the Overflow Valve and Too High at the Filter

    Possible Cause

    Remedy

    The main fuel filter is leaking.‪

    Repair or replace the leaking main fuel filter.‪

    The O-ring in the main fuel filter is worn, missing, or incorrectly installed.‪

    Replace the O-ring, or install it correctly.‪

    The main fuel filter cap is loose.‪

    Tighten the to cap 25 N·m (18 lb·ft).‪

    At one or more of the fuel injectors, the transfer tube is leaking, cracked, or incorrectly installed.‪

    Replace the transfer tube(s), or install it correctly.‪

    One or more fuel injectors are leaking, or cracked.‪

    Replace the fuel injector(s).‪

    Table 5. Problem — Fuel Flow Quantity is Too Low at the Overflow Valve and Too High at the Filter

    Problem — Fuel Flow Quantity is Too Low at the Overflow Valve and Within Range at the Filter

    Possible Cause

    Remedy

    The filter element in the fuel pre-filter is blocked.‪

    Replace the filter element.‪

    The filter element in the main fuel filter is blocked or contaminated.‪

    Clean the inside of the main fuel filter housing. Replace the filter element.‪

    The fuel feed lines are kinked or blocked.‪

    Inspect the lines, fittings, and check valve for blockage. Repair any kinks and replace the lines.‪

    The suction pipe or the strainer at the fuel level is blocked, or touching the bottom of the fuel tank.‪

    Open the fuel fill cap. Inspect the suction pipe and strainer. Remove any blockages, and reposition the suction pipe, if necessary. Remove the fuel level sensor and replace it if necessary.‪

    The check valve in the fuel feed line is blocked or is not sufficiently open (the opening flange is bent at the fitting).‪

    Repair/replace as necessary.‪

    The overflow valve is faulty, or the incorrect valve has been installed. The valve jams when closed as a result of wear or impurities in the fuel.‪

    Inspect the overflow valve. Replace as necessary.‪

    NOTE: Do not attempt to disassemble the overflow valve. The overflow valve cannot be repaired.‪

    Table 6. Problem — Fuel Flow Quantity is Too Low at the Overflow Valve and Within Range at the Filter


EPA07 MBE 4000 DDEC VI Troubleshooting Guide - 6SE568
Generated on 10-13-2008

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