823636 Mercury THROTTLE SHAFT (BOTTOM)

"Low Power/Poor Or No Response To Throttle".The probable root causes are listed below:
Derated engine
Fuel Position Multiplier
Personality Module
Throttle signal
Fuel supply
Air inlet restriction
Exhaust restriction
Leaks in air system
Faulty accessory equipmentPerform the following checks:
Connect the Caterpillar Electronic Technician (ET) and check for derate events that have been logged. A derate event will appear on the Cat ET if an active engine derate is occurring. In order to view active derates, go to the "Information" menu under "Status". The engine speed might be limited due to one of the following possible causes: altitude, exhaust temperatures that are high, air filters that are dirty, high crankcase pressure and high coolant temperature. Refer to the diagnostic procedure Troubleshooting, "Engine Monitoring System" in order to see the parameter settings for derates.
Refer to the diagnostic procedure Troubleshooting, "Fuel Position Mulitplier".
Verify that the correct Personality Module is installed and that the Personality Module is programmed correctly. Refer to the diagnostic procedure Troubleshooting, "System Configuration Parameters".
Use the Cat ET in order to monitor the status of the throttle. Observe the throttle position versus actual engine speed. The throttle position should be stable. The throttle position should reach 100 percent. Refer to the diagnostic functional test Troubleshooting, "Speed Control".
Check fuel lines for the following problems: restrictions, collapse and pinched line. Repair the lines and/or replace the lines. Refer to the Testing and Adjusting, "Fuel System Inspection".
Check the fuel tank for foreign objects which may block the fuel supply. Check for air in the low pressure fuel supply system after you perform the following procedures:
Replacing the fuel filters
Working on the low pressure fuel supply circuit
Replacing fuel injectors
Purge air from the low pressure fuel supply circuit with the hand priming pump and by cranking the engine in 30 second cycles. After you crank the engine, stop for two minutes. This will allow the starting motor to cool. Loosen the vent plug on the fuel return. The plug is located on the rear upper left side of the engine block. Hand prime the engine again if air in fuel continues. A sight glass in the low pressure supply line is helpful in diagnosing air in the fuel.
Check fuel quality. In temperatures below 0 °C (32 °F), check for solidified fuel (wax). Refer to Special Publication, SEBD0717, "Diesel Fuels And Your Engine". Check the fuel pressure while the engine is cranking. Check the fuel pressure at the filter. Refer to Testing and Adjusting, "Fuel Pressure". If pressure is low, check for plugged 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. Check for a combustion problem.
Check air inlet and exhaust systems for restrictions and/or leaks. Refer to the Testing and Adjusting, "Restriction of Air Inlet and Exhaust".
Observe the Event Screen on the Cat ET. In order to view active events, go to the "Events" menu under "Diagnostics". Check for an air filter restriction indicator. Replace plugged air filters and/or clean filters. Refer to the Operation and Maintenance Manual, "Engine Air Cleaner Differential Pressure - Check".
Check all flywheel or damper driven equipment for proper operation.