C15 and C18 Engines for Caterpillar Built Machines Caterpillar

Fuel Pressure Is High

Usage:

D9T NJH

The probable causes of high fuel pressure

Fuel pressure sensor
Fuel lines
Fuel transfer pump
Fuel return pressure regulator

Note: High fuel pressure may cause high fuel temperatures. Troubleshoot a code for high fuel pressure before troubleshooting a code for high fuel temperature.

Use this procedure in order to troubleshoot high fuel pressure. Use this procedure if one of the following event codes is active. Refer to Troubleshooting, "Event Codes" for information about event codes. For information on the engine monitoring system, refer to Troubleshooting, "Engine Monitoring System".

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Table 1
Diagnostic Trouble Codes
CDL Code	J1939 Code	Code Description (code descriptions may vary)	Comments
E096 (2)	5580-16	High Fuel Pressure	The code is logged. The fuel pressure is above the trip point pressure.

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Table 2
Troubleshooting Test Steps	Values	Results
1. Determine the Code A. Connect Cat ET to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools", if necessary. B. Determine if a diagnostic trouble code is present.	Diagnostic trouble code	Result: A E096 (2) or 5580-16 code is present. Proceed to Test Step 2. Result: A code other than E096 (2) or 5580-16 code is present. Troubleshoot the code. Refer to the proper troubleshooting procedure.

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Table 3
Required Tooling
8t-7860 Connector
110-6349 Fitting as
8t-0855 Pressure Gauge
6v-3990 Coupler

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Illustration 1	g02893220
(1) Fuel temperature sensor (2) Fuel sampling port (3) Fuel pressure sensor (4) Secondary fuel filter base

Do not use the fuel sampling port (2) for measuring the pressure. Follow the steps below.

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Table 4
Troubleshooting Test Steps	Values	Results
2. Check the Fuel Pressure Sensor A. Record the fuel pressure from Cat ET. Record the data in Table 5. B. Remove the fuel pressure sensor (3). C. Install an 8T-7860 Connector into the port of the pressure sensor (3). D. Install the 110-6349 Fitting as onto the 8T-7860 Connector. E. Install a 8T-0855 Pressure Gauge onto a 6V-3990 Coupler. F. Install the 6V-3990 Coupler onto the 110-6349 Fitting as. After the pressure sensor is removed, a code for low fuel pressure will become active. Reset all active codes and clear all logged codes by cycling the keyswitch to the Off position, after the sensor is reinstalled. G. Record the fuel pressure on the pressure gauge. Record the data in Table 5.	Fuel pressure	Result: The gauge value of the fuel pressure is within 137 kPa (20 psi) of the fuel pressure reading shown in ET. Proceed to Test Step 3. Result: The gauge value of the fuel pressure is not within 137 kPa (20 psi) of the fuel pressure reading shown in ET. Replace the pressure sensor. Reset all active codes and clear all logged codes by cycling the keyswitch to the Off position. Verify that the problem has been resolved. If the problem is not resolved, proceed to Test Step 3.

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Table 5
Engine RPM	Fuel pressure from Cat ET	Fuel pressure from the mechanical gauge
800
1800

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Illustration 2	g02893396
Fuel supply lines

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Illustration 3	g02893278
Return fuel line

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Table 6
Troubleshooting Test Steps	Values	Results
3. Inspect the Fuel Supply Lines A. Visually inspect the fuel lines between the primary filter base and the inlet to the cylinder head. 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.	Restrictions, pinching, and swelling	Result: The fuel lines and the cooler (if equipped) are OK. Proceed to Test Step 4. Result: The fuel lines and the cooler (if equipped) are not OK. Make the necessary repairs. Reset all active codes and clear all logged codes by cycling the keyswitch to the Off position. Verify that the problem has been resolved. If the problem is not resolved, proceed to Test Step 4.

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Illustration 4	g02893398
(5) Return fuel pressure regulator

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Table 7
Troubleshooting Test Steps	Values	Results
4. Replace the Return Fuel Pressure Regulator A. Replace the fuel pressure regulator.	Fuel pressure regulator	Result: The regulator was replaced. Reset all active codes and clear all logged codes by cycling the keyswitch to the Off position. Verify that the problem is resolved. If the problem is not resolved, proceed to Test Step 5.

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Illustration 5	g02893400
Typical fuel transfer pump (6) Relief valve

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Table 8
Troubleshooting Test Steps	Values	Results
5. Inspect the Relief Valve for the Fuel Transfer Pump A. Inspect the relief valve for the transfer pump. The spring must move freely.	Relief valve	Result: The relief valve is stuck closed. Replace the fuel transfer pump. Reset all active codes and clear all logged codes by cycling the keyswitch to the Off position. Verify that the problem has been resolved. Result: The relief valve is OK. Clean the relief valve and reinstall the relief valve. Reset all active codes and clear all logged codes by cycling the keyswitch to the Off position. Verify that the problem has been resolved.

Complete the procedure in the order in which the steps are listed.

If the procedure corrected the issue, return the engine to service.

If the procedure did not correct the issue, Contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).