19725 Mercury ELBOW (QTY. OF 2 ON 55)

Probable Causes
Cold mode
Active engine derates
Throttle signal from the throttle position sensor
Turbocharger outlet pressure sensor (intake manifold air), Rated fuel position and/or FRC fuel position
Fuel supply
Air inlet and exhaust system
Accessory equipmentRecommended Actions
Cold Mode
Use Caterpillar Electronic Technician (ET) in order to determine the status of cold mode. Cold mode operation may cause the engine to run rough and the engine power may be limited. Cold mode is displayed in the second engine status box on any Cat ET status screen. The engine will remain in cold mode for the following conditions.
Coolant temperature is below 18 °C (64 °F).
The engine is not cranking.
The engine has been running less than 14 minutes.Active Engine Derate
If an active derate occurs, the warning lamp will flash. "Engine Derate" will appear in the first engine status box on any Cat ET status screen. Verify that the set points for "Derate" that are in the programmable monitoring system have been programmed to the values that are correct. An SPN-FMI code will appear for an active derate on a J1939 receiving device that will display SPN diagnostic codes.Throttle Signal from the Throttle Position Sensor
Verify that the "Top Engine Limit" and "High Idle" are programmed to the values that are correct. Monitor the parameters for the throttle on Cat ET. Refer to table 1 for the values of the parameters.
Table 1
Throttle Parameters "Desired Engine Speed" "Throttle Position"
"Low Idle" Programmed to "low idle" 0%
"High Idle" Programmed to "high idle" 100% The "Desired Engine Speed" and the "Throttle Position" should increase linearly. Both parameters should increase steadily to the programmed "High Idle". The desired engine speed and the throttle position should decrease linearly. Both parameters should decrease steadily to the programmed "Low Idle". Refer to Troubleshooting, "Throttle Position Sensor Circuit - Test" for additional information.Turbocharger Outlet Pressure Sensor (Intake Manifold Air), Rated Fuel Position and/or FRC Fuel Position
During operation at full load, monitor "Fuel Position" and "Rated Fuel Limit" on the Cat ET status screen. If "Fuel Position" does not equal "Rated Fuel Limit" then check the air inlet manifold pressure.
Verify that there are no active diagnostic codes that are associated with the turbocharger outlet pressure sensor (intake manifold air) or with the atmospheric pressure sensor.
Monitor turbocharger outlet pressure on the Cat ET status screen and atmospheric pressure for normal operation. Note: Atmospheric pressure is not a default parameter on a Cat ET status screen. A new parameter screen must be set up in order to monitor the atmospheric pressure sensor.Fuel Supply
Check for active event codes. The following event codes may be active: EID 095 Flash Code 63 fuel filter restriction warning and EID 096 Flash Code 63 high fuel pressure.
Check the fuel lines for the following problems: restrictions, collapsed lines and pinched lines. If problems are found with the fuel lines, repair the lines and/or replace the lines.
Check the fuel tank for foreign objects which may block the fuel supply.
Check for air in the low pressure fuel supply 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
Purge air from the low pressure fuel supply circuit. Refer to Operation and Maintenance Manual, "Fuel System - Prime" for the correct procedure. Note: 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 Instruction, SEBD0717, "Diesel Fuels And Your Engine".
Check the fuel pressure during engine cranking. Check the fuel pressure on the outlet side of the fuel filter. 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. Air Inlet and Exhaust System
Clean plugged air filters or replace plugged air filters. Refer to the Operation and Maintenance Manual.
Check the air inlet and exhaust system for restrictions and/or leaks. Refer to Testing and Adjusting, "Air Inlet and Exhaust System". Accessory Equipment
Check all accessory equipment for problems that may create excessive load on the engine. Repair any damaged components or replace any damaged components.