34863 Mercury NUT

Probable Causes
Diagnostic codes
Electrical connectors
Fuel supply Air inlet and exhaust system
Throttle signal
Cold mode
Injection actuation pressure
Unit injectorsRecommended Actions
Note: If the symptom only occurs under certain operating conditions (high idle, full load, engine operating temperature, etc.), test the engine under those conditions. Troubleshooting the symptom under other conditions can give misleading results.
Table 1
Troubleshooting Test Steps Values Results
1. Active Codes and Logged Codes
A. Establish communication between Cat Electronic Technician (ET) and the Electronic Control Module (ECM).
B. Monitor the diagnostic codes on Cat ET. Check for active diagnostic codes.
Note: Wait at least 30 seconds in order for diagnostic codes to become active.
Codes
Result: There are active codes.
Repair: Troubleshoot any active diagnostic codes before continuing with this procedure.
There are no active codes
2. Check the condition of the connectors at the ECM.
A. Check for the correct installations of the J2/P2 ECM connectors.
B. Check the J300/P300 injector solenoid harness connector.
Electrical Connectors
Result: There is no problem in the connectors and/or wiring.
Proceed to Test Step 3.
Result: There is a problem in the connectors and/or wiring.
Repair: Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
3. Fuel Quality
A. Check the fuel lines for the following problems:
- Restrictions
- Collapsed Lines
- Pinched Lines
B. Check the fuel tank for debris or foreign objects which may block the fuel supply.
C. Check for air in the low-pressure fuel supply circuit. Refer to Systems Operation/Testing and Adjusting.
Fuel
Result: The fuel system is operating properly.
Proceed to Test Step 4.
Results: The fuel system is not operating properly.
Repair: Make the necessary repairs.
4. Restriction in the Air Inlet and Exhaust System
A. Check the air filter restriction indicator, if equipped. Clean plugged air filter or replace plugged air filters. Refer to the Operation and Maintenance Manual.
B. Check the air inlet and exhaust system for restrictions and/or leaks.
Restrictions
Result: There are restrictions in the air inlet or exhaust system.
Repair: Make the necessary repairs. Verify that the repair eliminated the problem.
Refer to Systems Operation/Testing and Adjusting.
Result: There are no restrictions in the air inlet or exhaust system.
Proceed to Test Step 5.
5. Throttle Signal
A. Monitor the status for "Throttle Position" on Cat ET.
B. 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 stable and 0 percent at low idle and 100 percent at high idle.
Proceed to Test Step 6.
Result: The throttle signal is not stable.
Repair: Make the necessary repair. Refer to the appropriate circuit test.
Verify that the repair eliminated the problem.
6. Cold Mode Operation
During cold mode operation, condensation maybe be present and is normal.
A. Cold mode is activated whenever the engine coolant temperature falls below a predetermined value. Monitor the status screen on Cat ET in order to verify that the engine has exited cold mode. Observe the reading for coolant temperature on Cat ET.
Cold Mode
Result: The engine is operating in cold mode.
Repair: This is normal operation. Return the engine to service.
Result: The engine is not operating in cold mode.
Proceed to Test Step 7.
Injection Actuation Pressure
Note: Refer to the procedure in Special Instruction, REHS3819, "Procedure for Troubleshooting and Cleaning the Oil Rail System for the Hydraulic Electronic Unit Injector". Verify that the repair eliminates the problem.Unit Injectors
Note: Refer to procedure in Special Instruction, REHS3819, "Procedure for Troubleshooting and Cleaning the Oil Rail System for the Hydraulic Electronic Unit Injector". Verify that the repair eliminates the problem.