C7 and C9 On-Highway Engines 0094-01 Low Fuel Pressure Warning (63) Caterpillar

Conditions Which Generate This Code:

Note: This diagnostic code represents an event. This diagnostic code does not represent an electronic system fault.

The Engine Control Module (ECM) detects all of the following conditions:

• Engine speed exceeds low idle rpm by at least 100 RPM.

• Fuel pressure in the low pressure fuel system is less than 150 kPa (22 psi).

The check engine lamp will illuminate after fifteen seconds of operation within the conditions that are mentioned above.

This code will also become active if a 94-03 Fuel Pressure Short Circuit becomes active.

System Response:

Factory passwords are required to clear this diagnostic code.

Note: The diagnostic code will be reset if the fuel pressure in the low pressure fuel system maintains 175 kPa (25 psi) for two minutes.

Possible Performance Effect:

Engine torque will be derated while the check engine lamp is illuminated.

The injection actuation pressure will be limited while the check engine lamp is illuminated.

Troubleshooting:

This diagnostic code indicates a low fuel pressure in the low pressure fuel system. This diagnostic code does not indicate a problem with the ECM or the fuel pressure sensor.

Test Step 1. Check the Fuel Level

Check the fuel level.

Expected Result:

The fuel level is OK.

Results:

• OK - The fuel level is OK. Proceed to Test Step 2.

• Not OK - The fuel level is low.

  Repair: Fill the fuel tanks with fuel.

  Verify that the repair eliminates the problem.

  STOP

Test Step 2. Verify Proper Sensor Installation

1. Check the installation of the fuel pressure sensor.

2. Check the wiring of the fuel pressure sensor. Refer to the engine's Electrical Schematic. Ensure that all of the wires and the connectors are properly connected.

Expected Result:

The sensor is properly installed and the wiring is correct.

Results:

• OK - The sensor is properly installed and the wiring is correct. Proceed to Test Step 3.

• Not OK - The sensor is not properly installed and/or the wiring is incorrect.

  Repair: Install the fuel pressure sensor properly. Repair the wiring and/or the connectors.

  Verify that the repair eliminates the problem.

  STOP

Test Step 3. Verify the Operation of the Fuel Pressure Sensor

1. Turn the keyswitch to the OFF position.

2. Remove the fuel pressure sensor.

3. Install a 1U-5470 Engine Pressure Group into the low pressure fuel system with a Tee fitting in the port for the fuel pressure sensor.

4. Connect the fuel pressure sensor to the Tee fitting.

5. Monitor the status for "Fuel Pressure" on Cat ET.

6. Start the engine.

7. Compare the pressure reading on the gauge to the pressure reading on Cat ET.

Expected Result:

The pressure readings are within 35 kPa (5.0 psi) of each other.

Results:

• OK - The sensor is functioning properly.

  Repair: There is a mechanical problem with the low pressure fuel system.

  Check the low pressure fuel system for the following conditions:

  • Low fuel pressure

  • Fuel filters that are plugged

  • Air in the fuel

  • Deterioration or plugging of the fuel lines
  Refer to the appropriate section in the Systems Operation/Testing and Adjusting for information that relates to testing the low pressure fuel system.

  Verify that the repair eliminates the problem.

  STOP

• Not OK - The sensor is not functioning properly.

  Repair: Temporarily install a new fuel pressure sensor.

  If the new sensor repairs the problem, reinstall the suspect sensor.

  If the problem returns, replace the sensor.

  Verify that the repair eliminates the problem.

  STOP