3524B Engines for Off-Highway Trucks Caterpillar

The Electronic Control Module (ECM) detects the following condition:

• The fuel filter differential pressure is above the default pressure of 124 kPa (18 psi) for the default time of 30 seconds.

System Response:

The ECM will log the event. The warning for the fuel filter differential pressure becomes active when the fuel filter differential pressure exceeds the default trip point of 124 kPa (18 psi). The warning becomes inactive when the fuel filter differential pressure decreases below 83 kPa (12 psi).

Possible Performance Effect:

• None

Troubleshooting:

• There may be a problem with the fuel system.

• There may be a problem with the filtered fuel sensor or the unfiltered fuel sensor.

Test Step 1. Check for "ACTIVE" Diagnostic Codes.

1. Start the Caterpillar Electronic Technician (ET).

2. Turn the main power to the ON position. The engine should be OFF.

3. Check for any Active Diagnostic Codes or Logged Diagnostic Codes.

Expected Result:

There should be no diagnostic codes that are present.

Results:

• OK - There are no diagnostic codes that are present. Proceed to Test Step 2.

• Not OK - There are diagnostic codes that are present.

  Repair: Repair the diagnostic codes that are present. Refer to the appropriate topic in the "Troubleshooting With a Diagnostic Code" section of this manual. Ensure that the repair eliminates the problem.

  STOP

Test Step 2. Perform a Check of the Fuel System.

1. Check the fuel tank for foreign objects which may block the fuel supply. Check for air in the low pressure fuel supply system after you perform the following procedures:

   • Replacing the fuel filters

   • Working on the low pressure fuel supply circuit

   • Replacing fuel injectors

2. Purge air from the low pressure fuel supply circuit with the hand priming pump and by cranking the engine in 30 second cycles. After you crank the engine, stop for two minutes. This will allow the starting motor to cool. Loosen the vent plug on the fuel return. The plug is located on the rear upper left side of the engine block. Hand prime the engine again if air in fuel continues. A sight glass in the low pressure supply line is helpful in diagnosing air in the fuel.

3. Check fuel quality. In temperatures below 0 °C (32 °F), check for solidified fuel (wax). Refer to Special Publication, SEBD0717, "Diesel Fuels And Your Engine". Check the fuel pressure while the engine is cranking. Check the fuel pressure at the filter. Refer to the Testing and Adjusting manual for the correct fuel pressure for your engine. If the pressure is low, check for plugged fuel filters. If the fuel pressure is still low, check the following items: fuel transfer pump, fuel transfer pump coupling and fuel pressure regulating valve. Check for a combustion problem.

Expected Result:

There are no problems with the fuel system.

Results:

• OK - There may be an intermittent problem.

  Repair: Monitor the operation of the engine. Repair the problem. Ensure that the repair eliminates the problem.

  STOP

• Not OK - There are problems with the fuel system.

  Repair: Repair the problem. Ensure that the repair eliminates the problem.

  STOP