56772 Mercruiser PLUG,CHOKE HOUSING

Recommended Repairs
Table 1
Troubleshooting Test Steps Values Results
1. Check for Codes
A. Connect Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Download the "Product Status Report" from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes.
C. Determine if the diagnostic trouble code that directed to this procedure is present.
D. Look for active diagnostic codes that are associated with the system for the event code that directed to this procedure.
Codes
Result: An associated code is present.
Repair: Troubleshoot any associated codes before continuing with this test.
Result: An associated code is NOT present.
Proceed to the next step.
2. Check for Excessive Load
A. Ensure that the load is not excessive. If necessary, disengage the driven equipment and test the engine.
Excessive Load
Result: No excessive load on the engine.
Proceed to the next step.
Result: The engine has an excessive load.
Repair: Remedy the cause of the excessive load.
3. Check the Base Timing
A. Verify that the base timing is correct. Refer to Systems Operation/Testing and Adjusting, "Ignition Timing - Adjust"
Base Timing
Result: The Base Timing is correct.
Proceed to the next step.
Result: The Base Timing is NOT correct.
Repair: Correct the Base Timing.
4. Check the Fuel Supply
A. Make sure that fuel is supplied at a sufficient pressure that is stable. Make sure that the size of the fuel line is sufficient. Inspect the fuel system for leaks.
The following conditions can cause the engine to malfunction:
- Low fuel pressure
- High fuel pressure
- Poor fuel quality
B. Make sure that the fuel pressure is correct. When possible, interview the operator to determine if fuel quality is in question. Try to determine if the source of the fuel was changed.
Inspect the fuel system components:
- Fuel filter
- Gas pressure regulator
- Gas shutoff valve
- Fuel metering valve
Fuel
Result: The fuel supply is OK.
Proceed to the next step.
Result: A faulty component was identified.
Repair: Repair or replace the faulty component.
5. Check the Ignition System
A. Ensure that current parts are used for the following components:
- Transformers
- Extenders
- Spark plugs
Inspect the ignition system for the following conditions:
1. Check the connection between the ignition transformer and the extender. A loose connection can cause arcing and misfires.
2. Check the connection between the extender and the spark plug for a loose connection or for pin holes that are caused by arcing. Both conditions can cause misfires.
3. Check the extender for corrosion on the spring. Corrosion may cause arcing through the extender.
4. Check for corrosion on the terminal of the spark plug and check for wear on the electrode. Both conditions can cause misfires.
Excessive moisture can cause misfire.
Maintain the spark plug according to the engine Operation and Maintenance Manual.
5. Check the ignition system components visually.
Swap coil with adjacent cylinder, start engine, and return to load point where initial failure occurred. If failure follows the coil replace the coil, if the failure stays with the original cylinder replace the spark plug.
Ignition System
Result: The Ignition System is OK.
Proceed to the next step.
Result: A faulty component was identified.
Repair: Repair or replace the faulty component.
Result: Worn spark plug
Repair: If secondary voltage on any cylinder is at or above 100% change spark plug.
6. Check the Air/Fuel Ratio
A. Verify that the exhaust emissions are correct. Refer to Systems Operation/Testing and Adjusting, "Air/Fuel Ratio Control - Adjust".
Air/Fuel Ratio
Result: The Air/Fuel Ratio is correct.
Proceed to the next step.
Result: The Air/Fuel Ratio is NOT correct.
Repair: Correct the Air/Fuel Ratio.
7. Check the Governor Adjustment
A. The governor parameters must be programmed with the values that provide stable operation. Refer to Systems Operation/Testing and Adjusting, "Engine Governing - Adjust".
Governor Adjustment
Result: The Governor Adjustment is correct.
Proceed to the next step.
Result: The Governor Adjustment is NOT correct.
Repair: Correct the Governor Adjustment.
8. Check for Binding of the Throttle Actuator
A. Set the engine control to the OFF/RESET mode.
B. Remove the electrical power from the engine.
C. Move the throttle plate while you feel the motion. If the motion is sticky and/or rough, investigate the cause of the binding. Make the necessary repairs.
Binding
Result: The actuator is OK.
Proceed to the next step.
Result: The actuator is NOT OK.
Repair: Remedy the cause of the binding.
9. Check for Binding of the Wastegate
A. Set the engine control to the OFF/RESET mode.
B. Remove the electrical power from the engine.
C. Move the wastegate while you feel the motion. If the motion is sticky and/or rough, investigate the cause of the binding. Make the necessary repairs.
Binding
Result: The actuator is OK.
Proceed to the next step.
Result: The actuator is NOT OK.
Repair: Remedy the cause of the binding.
10. Check for Binding of the Turbocharger Compressor Bypass Valve
A. Set the engine control to the OFF/RESET mode.
B. Remove the electrical power from the engine.
C. Move the bypass valve while you feel the motion. If the motion is sticky and/or rough, investigate the cause of the binding. Make the necessary repairs.
Binding
Result: The actuator is OK.
Proceed to the next step.
Result: The actuator is NOT OK.
Repair: Remedy the cause of the binding.
11. Check for Incorrect Valve Lash
A. Check the valve lash. Refer to Systems Operation, Testing and Adjusting, "Valve Lash and Valve Bridge Adjustment".
Lash
Result: The lash is OK.
Proceed to the next step.
Result: The lash is NOT OK.
Repair: Adjust the lash.
12. Check the Cylinder Head and Related Components
A. Measure the cylinder compression. Refer to the engine Operation and Maintenance Manual, "Cylinder Pressure - Measure/Record".
B.Inspect the components of the valve train for good condition. Check for signs of damage and/or of wear to the valves, cylinder head gasket, and related components. Inspect the condition of the camshafts. If a camshaft is replaced, new valve lifters must be installed.
Component
Result: A faulty component was identified.
Repair: Repair or replace the faulty component.