Section 3.3 Test #1 Downstream Pressure Test

Section 3.3
Test #1 Downstream Pressure Test

The following test set-up and test will determine the downstream fuel pressure.‪

Section 3.3.1
Test #1 Set-Up

Do the following set-up steps for the downstream pressure test.‪

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 1. Fuel Temperature Sensor‪

Figure 1. Fuel Temperature Sensor Location

  1. Disconnect the engine wiring harness connector from the fuel temperature sensor. See Figure "Fuel Temperature Sensor Location" .
  2. Remove the fuel temperature sensor.
  3. Install the disconnected fuel temperature sensor into the engine wiring harness and tie it out of the way.
  4. Install the adaptor and seal from the fuel adaptor parts kit (J-46377-A), in the fuel temperature sensor location and tighten adaptor securely. See Figure "Fuel Adaptor Parts Kit J-46377–A" , and see Figure " Test #1 Adaptor Set-up" .
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    Figure 2. Fuel Adaptor Parts Kit J-46377–A

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     1. Adaptor form Kit J-46377‪

     2. Banjo Fitting‪

     3. Electronic Unit Pump‪

     4. High Pressure Line J-46372‪

    Figure 3. Test #1 Adaptor Set-up

  5. Attach the banjo fitting and banjo bolt from the fuel adaptor kit (J-46377) into the adaptor. See Figure " Test #1 Adaptor Set-up" .
  6. Connect the high-pressure fuel line (J-46372) and gauge (J-46378) to the adaptor.

Section 3.3.2
Performing Test #1 Downstream Pressure Test

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.‪

    warning

    ENGINE EXHAUST

    To avoid injury from inhaling engine exhaust, always operate the engine in a well-ventilated area. Engine exhaust is toxic.‪

  2. Start the engine and run it at idle, 600 to 650 rpm.
  3. Record the fuel pressure reading on the high-pressure gauge. The gauge should read between 400-500 kPa (58.0–72.5 psi).
    1. If the fuel pressure is too low, perform test #3: Flow Test-At Fuel Filter, and correct the problem. Refer to "3.5 Test #3 Flow Test — At Fuel Filter" .
    2. If pressure is within specifications got to step .
  4. Increase the engine speed to 1900 rpm.
  5. Measure and record the fuel pressure on the high-pressure gauge. The gauge should read from 400-650 kPa (58–94 psi).
    1. If the fuel pressure is within limits, perform test #2: Fuel Pressure Test at the Fuel Filter, and correct the problem. Refer to "3.4 Test #2 Fuel Pressure Test At the Fuel Filter" .
    2. If the fuel pressure is too low, perform test #3: Flow Test-At Fuel Filter, and correct the problem. Refer to "3.5 Test #3 Flow Test — At Fuel Filter" .
    3. If the fuel pressure is too high, see the causes listed in Table "Problem — Fuel Pressure is Too High Downstream of the Fuel Filter" , “Problem-The Fuel Pressure is Too High Downstream of the Fuel Filter,” and correct the problem. Make any necessary repairs and replacements.
  6. Remove all test equipment. Install the fuel temperature sensor, torque the sensor to 30 N·m (22 lb·ft). Reconnect the fuel temperature sensor to the engine harness.
  7. Ensure the fuel fill cap is tightly closed and the vehicle has been restored to operating condition.

    Problem — The Fuel Pressure is Too High Downstream of the Fuel Filter

    Possible Cause

    Remedy

    The continuous ventilation port in the cap of the main fuel filter is blocked.‪

    Inspect the continuous ventilation port for blockage. Clean the port and replace the cap if necessary.‪

    The fuel drain lines downstream of the main filter housing are kinked or blocked.‪

    Repair/Replace as necessary.‪

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

    Repair/Replace as necessary.‪

    The fuel return line and/or strainer at the fuel level sensor is blocked or kinked.‪

    Remove the fuel level sensor and repair or replace the line or strainer, 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 5. Problem — Fuel Pressure is Too High Downstream of the Fuel Filter


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

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