99057M Mariner DAMPER

Recommended Repairs
Note: If the symptom only occurs under certain operating conditions (high idle, full load, engine operating temperature, etc), test the engine under the conditions. Troubleshooting the symptom under other conditions can give misleading results.Cold Cylinder
Locate the misfiring cylinder. Check the following components for failure: spark plug, extender, ignition transformer and primary wiring. Inspect the extender for signs of pin holes and/or arcing.Refer to Troubleshooting, "Ignition Transformers Secondary Circuit and Spark Plugs".Electrical Connectors or Power Supply
There may be an intermittent interruption of power. Check the wiring harnesses and the connectors. Inspect the connectors in the terminal boxes. Inspect the power supply connections and the ground.Inspect the wiring from the power supply to the control modules. Refer to Troubleshooting, "Electrical Power Supply".Ignition System
Inspect the ignition transformers for the following items: loose connections, moisture, short circuits and open circuits. Inspect the primary wiring and the secondary electrical connections.Make sure that the correct transformers and spark plugs are installed. Inspect the extenders for signs of pin holes and of arcing.Maintain the spark plug according to the engine's Operation and Maintenance Manual.Make sure that the ignition timing is correct.Fuel Supply
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 qualityMake sure that the fuel pressure is correct. When possible, interview the operator in order 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 and fuel metering valve. Verify that the system's components are operating correctly.Replace the fuel filter, if necessary.Air/Fuel Ratio
An air/fuel mixture that is too rich or too lean will have an adverse effect on engine operation. Verify that the exhaust emissions are correct. Refer to Systems Operation/Testing and Adjusting, "Air/Fuel Ratio Control - Adjust".A change in the fuel energy content will change the air/fuel ratio. Obtain a fuel analysis.The fuel supply pressure must be adequate and stable.Governor Adjustment
The governor's parameters must be programmed with the values that provide stable operation. Refer to Systems Operation/Testing and Adjusting, "Engine Governing - Adjust".Air Inlet Restriction
The maximum allowable air inlet restriction is 3.75 kPa (15 inches of H2O). If the indication is higher than the maximum permissible restriction, clean the filter element or install a new filter element. Check the restriction again. If the restriction remains too high, inspect the air inlet piping for obstructions.For more information, refer to Systems Operation/Testing and Adjusting, "Restriction of Air Inlet and Exhaust".Exhaust Restriction
Check for restriction in the exhaust system. Refer to Systems Operation/Testing and Adjusting, "Restriction of Air Inlet and Exhaust".Check for Binding of the Throttle Actuator
Set the engine control to the OFF/RESET mode. Switch the 35 amp circuit breaker OFF. 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.Incorrect Valve Lash
Check the valve lash. Refer to Systems Operation, Testing And Adjusting, "Valve Lash and Valve Bridge Adjustment".Cylinder Head and Related Components
Measure the cylinder compression. Refer to the engine's Operation and Maintenance Manual, "Cylinder Pressure - Measure/Record".Inspect the components of the valve train for good condition. Check for signs of damage and/or wear to the valves, cylinder head gasket, etc. Inspect the condition of the camshafts. If a camshaft is replaced, new valve lifters must be installed.Throttle
Make sure that the throttle actuator is operating properly. If the motion of the actuator is sticky and/or rough, service the actuator.