12431T Mercury PLUG

Recommended Actions
Note: If the problem only occurs under certain conditions, test the engine under those conditions. Examples of certain conditions are high engine speed, full load and engine operating temperature. Troubleshooting the symptoms under other conditions can give misleading results.
Table 1
Troubleshooting Test Steps Values Results
1. Check for Diagnostic and Event Codes
A. Certain diagnostic codes and/or event codes may cause poor performance. Connect Cat® Electronic Technician (ET) and check for active codes and/or for logged codes.
Diagnostic and Event Codes
Result: There are no diagnostic or event codes.
Proceed to Test Step 2.
Result: There are diagnostic and/or event codes.
Repair: Troubleshoot any codes before continuing with this procedure.
2. Check for Cold Mode
A. Use Cat ET to verify that the engine has exited cold mode. Cold mode operation may cause the engine to run rough and engine power may be limited.
B. Observe the coolant temperature on the Cat ET status screen. Verify that the reading is valid.
Cold Mode
Result: The engine is not in cold mode.
Proceed to Test Step 3.
Result: The engine is in cold mode.
Repair: Troubleshoot the reason for the engine being in cold mode and make the necessary repairs.
3. Check the Throttle Signal
A. Monitor the status for "Throttle Position" on Cat ET. Verify that the status for "Throttle Position" is stable and that the engine is able to reach high idle speed.
Throttle Signal
Result: The throttle signal is OK.
Proceed to Test Step 4.
Result: The throttle signal is NOT OK.
Repair: Refer to the appropriate troubleshooting procedure for troubleshooting the throttle signal.
4. Check the Electrical Connectors
A. Check for correct installation of the J1/P1 and J2/P2 Electronic Control Module (ECM) connectors and the unit injector connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect".
Electrical Connectors
Result: The electrical connectors are OK.
Proceed to Test Step 5.
Result: The electrical connectors are NOT OK.
Repair: Repair or replace any damaged or worn components.
5. Check the Unit Injectors
A.Perform the "Injector Solenoid Test" on Cat ET in order to determine if all of the injector solenoids are being energized by the ECM.
B. Perform the "Cylinder Cutout Test" on Cat ET in order to identify any misfiring cylinder(s). Refer to Troubleshooting, "Injector Solenoids Circuit - Test" for more information.
Unit Injectors
Result: The unit injectors are OK.
Proceed to Test Step 6.
Result: The unit injectors are NOT OK.
Repair: Replace the unit injectors.
Table 2
"Fuel Position" = "Rated Fuel Limit"
and
"Fuel Position" < "FRC Fuel Limit"
Table 3
Troubleshooting Test Steps Values Results
6. Check the Intake Manifold Pressure Sensor
A. Monitor the status of "Fuel Position", "Rated Fuel Limit", and "FRC Fuel Limit" on Cat ET while the engine is operating under full load. These parameters should reflect the information that is contained in Table 2.
B. If "Fuel Position" equals "Rated Fuel Limit" and "Fuel Position" is less than "FRC Fuel Limit", the electronics are operating correctly. Otherwise, proceed with the next Step.
C. Monitor the status of "Intake Manifold Pressure" and "Atmospheric Pressure" for normal operation on Cat ET. When the engine is not running, the correct value for "Intake Manifold Pressure" is 0 kPa (0 psi).
Intake Manifold Pressure Sensor
Result: The intake manifold pressure sensor is OK.
Proceed to Test Step 7.
Result: The intake manifold pressure sensor is NOT OK.
Repair: Replace the intake manifold pressure sensor.
7. Check the Air Inlet and Exhaust System
A. Observe the indicator lamps. Check for an air filter restriction indicator. Clean plugged air filters or replace plugged air filters. Refer to the Operation and Maintenance Manual for additional information.
B. Check the air inlet and exhaust system for restrictions and/or for leaks. Refer to Systems Operation/Testing and Adjusting for information on inspecting the air inlet and exhaust system.
Air Inlet and Exhaust System
Result: The air inlet and exhaust system is OK.
Proceed to Test Step 8.
Result: The air inlet and exhaust system is NOT OK.
Repair: Repair or replace any worn or damaged components.
8. Check the Configuration Parameters
A. If the ECM has been replaced, compare the values on the Engine Information Plate to following parameters from Cat ET:
• FRC offset
• Full Load Setting (FLS)
• Full Torque Setting (FTS)
Configuration Parameters
Result: The configuration parameters are OK.
Proceed to Test Step 9.
Result: The configuration parameters are NOT OK.
Repair: Troubleshoot the cause for incorrect configuration parameters.
Do not crank the engine continuously for more than 30 seconds. Allow the starting motor to cool for two minutes before cranking the engine again.
Table 4
Troubleshooting Test Steps Values Results
9. Check the Fuel Supply
A. Check the fuel lines for the following problems: restrictions, collapsed lines and pinched lines. If problems are found with the fuel lines, repair the lines and/or replace the lines.
B. Check the fuel tank for foreign objects which may block the fuel supply.
C. Prime the fuel system if any of the following procedures have been performed:
• Replacement of the fuel filters
• Service on the low pressure fuel supply circuit
• Replacement of unit injectors
D. A sight glass in the low pressure supply line is helpful in diagnosing air in the fuel. Refer to Systems Operation/Testing and Adjusting for more information.
E. Cold weather adversely affects the characteristics of the fuel. Refer to the Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold weather operation.
F. Check the fuel pressure after the fuel filter while the engine is being cranked. Refer to Systems Operation/Testing and Adjusting for the correct pressure values. If the fuel pressure is low, replace the 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. Refer to Systems Operation/Testing and Adjusting for more information.
Fuel Supply
Result: The fuel supply is OK.
Return the engine to service.
Result: The fuel supply is NOT OK.
Repair: Repair or replace any damaged or worn components.