PUMP GP-PISTON 3259777 - Caterpillar

Probable Causes
Diagnostic codes
Accessory equipment
Fuel supply
Power Mode Control
Low compression (cylinder pressure)
Electronic unit injectorsRecommended Actions
Diagnostic Codes
Use one of the following methods to check for active diagnostic codes:
The electronic service tool
The display on the control panelElectronic Service Tool
Connect the electronic service tool to the diagnostic connector.
Check for active diagnostic codes on the electronic service tool.
Investigate any active codes before continuing with this procedure. Refer to Troubleshooting, "Troubleshooting with a Diagnostic Code".Display on the Control PanelNote: The following procedure is only applicable if the application is equipped with a display on the control panel.
Check the display on the control panel for active diagnostic codes.
Troubleshoot any active codes before continuing with this procedure. Refer to Troubleshooting, "Troubleshooting with a Diagnostic Code".Accessory Equipment
Check all accessory equipment for faults that may create excessive load on the engine. Repair any damaged components or replace any damaged components.If there are no faults with the accessory equipment, refer to "Power Mode Control".Power Mode Control
The power mode control is using the CAN data link. Refer to Troubleshooting, "CAN Data Link Circuit - Test".
If no faults are found on the CAN data link, check the engine speed dial. Refer to the Troubleshooting Guide for the machine application.
If there are no apparent faults, refer to "Fuel Supply".Fuel Supply
Visually check the fuel tank for fuel. The fuel gauge may be faulty.
Ensure that the fuel supply valve (if equipped) is in the full OPEN position.
If the temperature is below 0 °C (32 °F), check for solidified fuel (wax).
Check the primary filter/water separator for water in the fuel.
Check for fuel supply lines that are restricted.
Check that the low-pressure fuel lines are tight and secured properly.
Replace the in-line fuel strainer that is installed upstream of the Electric Fuel Lift Pump (EFLP).
Check that the EFLP is operating. If the EFLP is suspect, refer to Troubleshooting, "Fuel Pump Relay Circuit - Test".
Check the fuel filters.
Check the diesel fuel for contamination. Refer to Systems Operation, Testing, and Adjusting, "Fuel Quality - Test".
Check for air in the fuel system. Refer to Systems Operation, Testing, and Adjusting, "Air in Fuel - Test".
Ensure that the fuel system has been primed. Refer to Systems Operation, Testing, and Adjusting, "Fuel System - Prime".
Check the fuel pressure. Refer to Systems Operation, Testing, and Adjusting, "Fuel System Pressure - Test".
If necessary, repair any faults.
If there are no apparent faults, refer to "Low Compression (Cylinder Pressure)".Low Compression (Cylinder Pressure)
Perform a compression test. Refer to Systems Operation, Testing, and Adjusting, "Compression - Test ".
If low compression is noted on any cylinders, investigate the cause and rectify the cause.Possible causes of low compression are shown in the following list:
Loose glow plugs
Faulty piston
Faulty piston rings
Worn cylinder bores
Worn valves
Faulty cylinder head gasket
Damaged cylinder head
Perform all necessary repairs.
Ensure that the repairs have eliminated the faults.
If the repair does not eliminate the fault, refer to "Electronic Unit Injectors".Electronic Unit Injectors
Use the electronic service tool to perform the automatic "Cylinder Cut Out Test". If the compression test that was performed in "Low Compression (Cylinder Pressure)" was satisfactory, the "Cylinder Cut Out Test" will