62639A 1 Mercury GEAR AND SHAFT, THROTTLE CONTROL

Probable Causes
Diagnostic codes
Event codes
Turbocharger
Air inlet and exhaust restrictions
Throttle signal
Power supply for the Electronic Control Module (ECM)
Fuel supplyRecommended 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 the Cat® Electronic Technician (ET) and check for active codes and/or for logged codes.
Diagnostic and Event Codes
Result: There are no diagnostic or even codes.
Proceed to Test Step 2.
Result: There are diagnostic and/or event codes.
Repair: Troubleshoot the codes before continuing with this procedure.
2. Check the Operation of the Turbocharger
A. Ensure that the turbocharger is operating correctly. Periodic inspection and cleaning are recommended for the turbocharger compressor housing (inlet side).
Turbocharger
Result: The turbocharger is OK.
Proceed to Test Step 3.
Result: The turbocharger is NOT OK.
Repair: Repair or replace the turbocharger.
3. Check for Air Inlet and Exhaust System Restrictions
A. Check the air inlet system for the following problems: restrictions, collapsed and pinched line.
B. Check for an air filter restriction. Replace plugged air filters and/or clean filters. Repair any leaks.
Air Inlet and Exhaust System Restrictions
Result: The air inlet and exhaust system is OK.
Proceed to Test Step 4.
Result: The air inlet and exhaust system is NOT OK.
Repair: Repair or replace any damaged or worn components.
4. 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. Refer to the appropriate diagnostic test for your application:
• Troubleshooting, "Throttle Position Sensor Circuit - Test"
• Troubleshooting, "Throttle Switch Circuit - Test"
• Troubleshooting, "Speed Control - Test"
Throttle Signal
Result: The throttle signal is OK.
Proceed to Test Step 5.
Result: The throttle signal is NOT OK.
Repair: Troubleshoot the reason for an unstable throttle signal.
5. Check the ECM Power Supply
A. Inspect the circuit between the ECM and the batteries. Refer to the Electrical System Schematic. Inspect the wires, the connectors, and the components in the circuit. Refer to the diagnostic functional test Troubleshooting, "Electrical Power Supply Circuit - Test" for more information.
B. Inspect the circuit between the ECM and the keyswitch. Refer to the Electrical System Schematic. Inspect the wires, the connectors, and the components in the circuit. Refer to the diagnostic functional test Troubleshooting, "Electrical Power Supply Circuit - Test" for more information.
ECM
Result: The ECM power supply is OK.
Proceed to Test Step 6.
Result: The ECM power supply is NOT OK.
Repair: Repair or replace any damaged or worn components.
6. Check the Fuel Supply
A. Check the fuel lines for the following problems: restrictions, collapsed lines, and pinched 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. Check the fuel pressure after the fuel filter while the engine is being cranked. Refer to Systems Operation/Testing and Adjusting, "Fuel System" 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.