3512B Marine Auxiliary Engine Caterpillar

• Cold mode

• Coolant temperature sensor

• Fuel level

• Low Idle/High Idle switch

• Electrical connectors

• Injector solenoid

• Fuel consumption

• Air inlet restriction

• Electronic Control Module (ECM)

• Fuel supply

Perform the following tests in order:

1. Use the Caterpillar Electronic Technician (ET) in order to verify that the engine has exited cold mode. During Cold Mode, injection timing is modified. The cylinders may cut out. Cold Mode Cylinder Cutouts may cause variations in vibration and available power. This is normal operation.

2. Use the Cat ET in order to monitor the temperature of the coolant. If the reading is incorrect, refer to the diagnostic functional test Troubleshooting, "Engine Sensor Open/Short Test".

3. Monitor fuel level during engine operation. If a low fuel level causes the problem, maintain a higher fuel level.

4. Use the Cat ET in order to monitor the status of the Low Idle/High Idle switch. Observe the switch position. Move the switch from the Low Idle position to the High Idle position. The Cat ET should indicate the correct position. Refer to the diagnostic functional test Troubleshooting, "Low Idle/High Idle Switch".

5. Check for correct installation of the ECM connectors J2/P2 and Fuel Injector connector J4/P4 through J15/P15. Refer to the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".

6. Use the Cat ET to determine if any active diagnostic codes are present. Perform the Injector Solenoid Test. Observe that the injector solenoids are being energized on the Cat ET. Perform the Cylinder Cutout Test. Locate the misfiring cylinder. Refer to the diagnostic functional test Troubleshooting, "Injector Solenoids".

7. Use the Cat ET in order to monitor the engine status. Operate the engine under full load. Check Actual fuel and Max fuel. The Actual fuel consumption should be equal to Max fuel.

8. Check the air inlet and exhaust systems for the following problems: restrictions, collapse and pinched line. Repair the lines and/or replace the lines. Refer to Testing and Adjusting, "Air Inlet and Exhaust System".

   1. Observe the Check Engine Lamp. Check for a air filter restriction indicator. Replace plugged air filters and/or clean filters. Refer to the Testing and Adjusting, "Air Inlet and Exhaust System". Repair any leaks. Refer to the diagnostic functional test Troubleshooting, "Engine Sensor Open/Short Test".

9. If you have replaced the ECM, refer to the diagnostic procedure Troubleshooting, "Programming Parameters".

10. Check fuel lines for the following problems: restrictions, collapse and pinched line. Repair the lines and/or replace the lines. Refer to the Systems Operation, "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 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 at 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). Check the fuel pressure while the engine is cranking. Check the fuel pressure at the filter. Refer to Testing and Adjusting, "Fuel Pressure" for correct pressure values. 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 problem with the combustion system.