C9.3 Marine Propulsion Engine Caterpillar

Use this procedure to troubleshoot high fuel temperature. 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".

Note: Refer to Troubleshooting, "Cat ET Service Features" for information about service features.

Table 1

J1939 Code and Description	Comments
174-0 Engine Fuel Temperature 1 : Data High - Most Severe (3)	The fuel temperature sensor on the secondary filter head is higher than expected.
174–15 Engine Fuel Temperature 1 : Data High - Least Severe (1)	The fuel temperature sensor on the secondary filter head is higher than expected.
174–16 Engine Fuel Temperature 1 : Data High - Moderately Severe (2)	The fuel temperature sensor on the secondary filter head is higher than expected.

Table 2

Associated Diagnostic Trouble Codes
J1939 Code	Code Description
94	Engine Fuel Delivery Pressure
5580	Engine Filtered Fuel Delivery Absolute Pressure

Probable Causes

Probable causes of high fuel temperature.

• Associated codes

• Fuel level in the tank

• Restriction in the fuel lines

• Fuel cooler (if equipped)

• Fuel temperature sensor

• Fuel return pressure regulator

• Fuel injector

Recommended Actions

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

Table 3

Troubleshooting Test Steps	Values	Results
1. Determine the Code A. Establish communication between Cat® Electronic Technician (ET) and the Electronic Control Module (ECM) . Refer to Troubleshooting, "Electronic Service Tools", if necessary. B. Download the "Warranty Report" from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes. Check for active codes and check for logged codes on Cat ET. C. Check Cat ET for any associated codes that are listed in Table 2. Troubleshoot any active codes before continuing with this procedure.	Codes	Result: An associated code is not active or logged. Proceed to Test Step 2. Result: An associated code is active or logged. Repair: Troubleshoot any active codes before continuing with this procedure. If the problem is not resolved, proceed to Test Step 2.
2. Check the Fuel Level in the Fuel Tank A. Check the fuel level in the fuel tank.	Fuel Level	Result: The fuel level is acceptable. Proceed to Test Step 3. Result: The fuel level is not acceptable. Repair: Fill the tank. Verify that the problem has been resolved. If the problem has not been resolved, proceed to Test Step 3.

Illustration 1	g03814805
Fuel supply lines for inspection

Illustration 2	g03814817
Duplex Fuel Filters and Supply Lines Front View (If Equipped)

Illustration 3	g03814819
Duplex Fuel Filters and Supply Lines Rear View (If Equipped)

Illustration 4	g02163246
Cooling line from fuel high-pressure pump to injectors

Illustration 5	g03814884
Fuel return line to be inspected

Table 4

Troubleshooting Test Steps	Values	Results
3. Inspect the Fuel Supply Lines A. Visually inspect the fuel lines between the priming pump and the inlet to the cylinder head. Also, inspect the fuel cooler (if equipped) for dirt, debris, or damage. 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. B. Inspect the fuel cooler for dirt, debris, or damage.	Fuel Supply 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: Replace damaged fuel lines and/or fuel cooler. Remove dirt or debris from fuel cooler fins. Verify that the problem has been resolved. If the problem has not been resolved, proceed to Test Step 4.

Illustration 6	g03820721
Fuel cooler (If Equipped)

Illustration 7	g03814893
(1) Fuel temperature sensor

Illustration 8	g06032065
Duplex Fuel System (2) Pre Filter Pressure Sensor (3) Post Filter Temperature Sensor (4) Post Filter Pressure

Table 5

Troubleshooting Test Steps	Values	Results
4. Replace the Temperature Sensor A. Replace fuel temperature sensor (1). B. Check for active codes or logged codes.	Fuel Temperature Sensor	Result: A 174 code is active or logged. Proceed to Test Step 5. Result: A 174 code is not active or logged. Return the unit to service. If the problem is not resolved, proceed to Test Step 5.

Illustration 9	g06135460
(5) Fuel return pressure regulator

Table 6

Troubleshooting Test Steps	Values	Results
5. Replace the Fuel Return Pressure Regulator A. Replace the fuel return pressure regulator (2). Verify that the problem has been resolved.	Fuel Pressure Regulator	Result: The problem has not been resolved. Proceed to Test Step 6. Result: The problem has been resolved. Return the unit to service.
6. Perform a Fuel System Verification Test A. Perform a "Fuel System Verification Test" in Cat ET.	Fuel System verification Test	Result: The "Fuel System Verification Test" was not successful. Repair: Replace the identified injectors. Verify that all trim files are installed into the ECM correctly. Refer to Troubleshooting, "Injector Trim File - Install". Repeat the "Fuel System Verification Test" after making the necessary repairs. Repeat the process until all the injectors are operating properly. Result: The "Fuel System Verification Test" was successful. Return the unit 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).