C7 and C9 Industrial Engines Caterpillar

Use this procedure in order to troubleshoot high fuel pressure or use this procedure if the following event code is active. Refer to Troubleshooting, "Event Codes" for information about event codes.

Table 1

Diagnostic Trouble Codes
J1939 Code	CDL Code	Code Description (code descriptions may vary)	Comments
94-15	E096(1)	Engine Fuel Delivery Pressure : High - least severe (1)	The code is logged.
94-16	E096(2)	Engine Fuel Delivery Pressure : High - moderate severity (2)	The code is logged.
94-0	E096(3)	Engine Fuel Delivery Pressure : High - most severe (3)	The code is logged.

Probable Causes

• Fuel supply and return lines

• Fuel pressure sensor installation

• Fuel pressure sensor operation

• Fuel pressure regulator

• Fuel transfer pump relief valve

Recommended Actions

Note: The procedures have been listed in order of probability. Complete the procedures in order.

Table 2

Troubleshooting Test Steps	Values	Results
1. Inspect the Fuel Supply and Return Lines A. Visually inspect the fuel lines between the primary and secondary filter bases and the inlet to the fuel injection pump. Also, inspect the fuel cooler, if equipped. Inspect the fuel return line from the head to the fuel tank. Inspect the lines for restrictions, pinching, and swelling. Refer to Systems Operation/Testing and Adjusting, "Fuel System - Inspect", for additional information.	Inspect Lines	Result: The fuel lines and the cooler (if equipped) are OK. Proceed to Test Step 2. Result: The fuel lines and the cooler (if equipped) are not OK. Repair: Make the necessary repairs. Verify that the problem has been resolved. If the problem has not been resolved, proceed to Test Step 2.
2. Verify Correct Sensor Installation A. Check the installation of the fuel pressure sensor. B. Check the wiring of the fuel pressure sensor. Refer to the engine Electrical Schematic. Ensure that all of the wires and the connectors are properly connected.	Sensor installation	Result: The sensor is properly installed and the wiring is correct. Proceed to Test Step 3. Result: The sensor is not properly installed and/ or the wiring is incorrect. Repair: Install the fuel pressure sensor properly. Repair the wiring and/or the connectors.
3. Verify the Operation of the Fuel Pressure Sensor A. Turn the keyswitch to the OFF position. B. Remove the fuel pressure sensor. C. Install a suitable pressure gauge into the low-pressure fuel system with a tee fitting in the port for the fuel pressure sensor. D. Connect the fuel pressure sensor to the tee fitting. E. Monitor the status for "Fuel Pressure" on the electronic service tool. F. Crank the engine. G. Compare the pressure reading on the gauge to the pressure reading on the electronic service tool.	Within 35 kPa (5 psi)	Result: The pressure readings are within 35 kPa (5 psi) of each other. The sensor is functioning properly. Proceed to Test Step 4. Result: The pressure readings are not within 35 kPa (5 psi) of each other. The sensor is not functioning properly. Repair: Temporarily install a new fuel pressure sensor. If the new sensor repairs the problem, reinstall the suspect sensor. If the problem returns, replace the sensor.
4. Replace the Fuel Return Pressure Regulator A. Replace the fuel return pressure regulator. B. Inspect the anti-drain check valve for proper operation.	Replace Pressure Regulator	Result: The problem has been resolved. Return the engine to service. Result: The problem has not been resolved. Proceed to Test Step 5.
5. Inspect the Relief Valve for the Fuel Transfer Pump A. Inspect the relief valve for the transfer pump. The spring must move freely.	Transfer Pump	Result: The relief valve is stuck CLOSED. Repair: Replace the fuel transfer pump. Verify that the problem has been resolved. Result: The relief valve is OK. Repair: Clean the relief valve and reinstall the relief valve. Verify that the problem has been resolved.