HEAD GP-PUMP 3677557 - Caterpillar

Probable Causes
Engine derate or active codes
Cold mode
Throttle signal
Electrical connectors
Unit injectors
Boost pressure sensor
Air inlet and exhaust system
Parameters
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.Engine Derate or Active Codes
Some engine monitoring parameters that are capable of triggering an engine derate do not produce an event code. Connect Caterpillar Electronic Technician (ET) in order to check for a derate of the engine.Certain diagnostic codes and/or event codes may cause poor performance. Use Cat ET to check for active codes and for logged codes. Troubleshoot any codes that are present before continuing with this procedure.Note: Although a sensor's signal may be in the operational range of the sensor, the signal may not represent the actual reading. Use Cat ET to check that the pressures and the temperatures are fluctuating. Also check that the values are reasonable for the conditions that are present.Cold Mode
Use Cat ET to verify that the engine has exited cold mode. Cold mode operation may cause the engine to run rough and engine power may be limited.
Observe the coolant temperature on the Cat ET status screen. Verify that the reading is valid.Throttle Signal
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 Troubleshooting, "Speed Control - Test" for the correct procedure.Electrical Connectors
Check for correct installation of the J1/P1 and J2/P2 Electronic Control Module (ECM) connectors and the J300/P300 connectors for the unit injectors. Refer to Troubleshooting, "Electrical Connectors - Inspect".Unit Injectors
Perform the "Injector Solenoid Test" on Cat ET in order to determine if all of the injector solenoids are being energized by the ECM.
Perform the "Cylinder Cutout Test" on Cat ET in order to identify any misfiring cylinder(s). Refer to Troubleshooting, "Injector Solenoids Circuit - Test" for more information.Boost Pressure Sensor
Monitor the status of "Fuel Position", "Rated Fuel Limit", and "FRC Fuel Limit" on Cat ET while the engine is operating under full load. These parameters should reflect the information below.
Table 1
"Fuel Position" = "Rated Fuel Limit"    
and    
"Fuel Position" < "FRC Fuel Limit"    If "Fuel Position" equals "Rated Fuel Limit" and "Fuel Position" is less than "FRC Fuel Limit", the electronics are operating correctly. Otherwise, proceed with the next step.
Monitor the status of "Boost Pressure" and "Atmospheric Pressure" for normal operation on Cat ET. When the engine is not running, the correct value for "Boost Pressure" is 0 kPa (0 psi).Air Inlet and Exhaust System
Check for an air filter restriction. Clean plugged air filters or replace plugged air filters.
Check the air inlet and exhaust system for restrictions and/or for leaks.Parameters
If the ECM has been replaced, compare the values that are on the engine information plate to following parameters from Cat ET:
FRC offset
Full Load Setting (FLS)
Full Torque Setting (FTS)Fuel Supply
Visually check the