C9.3 Tier 4 Final Engines Caterpillar

Fuel Pressure Is High

Usage:

D6T 2B3

The probable causes of high fuel pressure

Fuel pressure sensors
Fuel lines
Fuel transfer pump
Fuel return pressure regulator

Use this procedure in order to troubleshoot high fuel pressure. Use this procedure if the following event code 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
J1939 Code	CDL Code	Code Description	Comments
94-16	E1218 (2)	High Unfiltered Fuel Pressure	The code is logged. The fuel pressure is above the trip point pressure.

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Table 2
Associated Diagnostic Trouble Codes
J1939 Code	CDL Code
5584	E390

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

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Table 3
Troubleshooting Test Steps	Values	Results
1. Determine the Code A. Connect Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools", if necessary. B. Download the "Warranty Report" from the engine Electronic Control Module (ECM) before performing any troubleshooting or clearing diagnostic trouble codes. C. Determine if a diagnostic trouble code is present.	Codes	Result: An E1218 (2) or 94-16 code is present. Proceed to Test Step 2. Result: A code other than an E1218 (2) or 94-16 code is present. Repair: Troubleshoot the code. Refer to the proper troubleshooting procedure.

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Illustration 1	g03758116
(1) Fuel temperature sensor (2) Fuel pressure sensor "A" (3) Fuel pressure sensor "B" (4) Fuel filter base

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Table 4
Troubleshooting Test Steps	Values	Results
2. Check Fuel Pressure Sensor "A" A. Record the unfiltered fuel pressure from Cat ET. Record the value in Table 6. B. Remove fuel pressure sensor "A" (2). C. Install a 5P-1318 Adapter into the port of the pressure sensor "A" (2). D. Install the 123-0783 Fluid Sampling Valve Gp onto the 5P-1318 Adapter. E. Install a 8T-0855 Pressure Gauge onto a 6V-3990 Coupler. F. Install the 6V-3990 Coupler onto the 123-0783 Fluid Sampling Valve Gp. G. Record the fuel pressure from the pressure gauge. Record the pressure in Table 6.	Pressure Sensor	Result: The gauge value of the fuel pressure is within 69 kPa (10 psi) of the unfiltered fuel pressure reading shown in Cat ET. Proceed to Test Step 3. Result: The gauge value of the fuel pressure is not within 69 kPa (10 psi) of the unfiltered fuel pressure reading shown in Cat ET. Repair: Replace the pressure sensor. Verify that the problem has been resolved. If the problem is not resolved, proceed to Test Step 3.

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Table 5
Required Tooling for Pressure Sensor "A"
5P-1318 Adapter
123-0783 Fluid Sampling Valve Gp
8T-0855 Pressure Gauge
6V-3990 Coupler

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Table 6
Engine RPM	Unfiltered fuel pressure from Cat ET	Fuel pressure from the mechanical gauge
800
1800

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Illustration 2	g02041759
Fuel supply lines

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Illustration 3	g02041781
Fuel return line

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Table 7
Troubleshooting Test Steps	Values	Results
3. Inspect the Fuel Supply and Return Lines A. Visually inspect the fuel lines between the primary filter base 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 4. 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 is not resolved, proceed to Test Step 4.

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Illustration 4	g02041814
(5) Return fuel pressure regulator

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Table 8
Troubleshooting Test Steps	Values	Results
4. Replace the Return Fuel Pressure Regulator A. Replace the fuel pressure regulator.	Pressure Regulator	Result: The regulator was replaced. Verify that the problem is resolved. If the problem is not resolved, proceed to Test Step 5.

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Illustration 5	g03758117
Typical fuel transfer pump (6) Relief valve

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Table 9
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.	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.