C175 Oil&Gas Offshore Engine Caterpillar

Fuel Pressure Is Low

Usage:

Use this procedure to troubleshoot a problem with low fuel pressure. Or, use this procedure if one of the following diagnostic codes is active.

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Table 1
J1939 Code and Description	CDL Code and Description	Comments
5578-14 Engine Fuel Delivery Absolute Pressure : Special Instruction	E489 (1) Intake Valve Actuation Pressure System Failure	The prelubrication cycle completed, but the fuel pressure after the secondary filter is lower than expected.
5580-17 Engine Filtered Fuel Delivery Absolute Pressure : Low - least severe (1)	E198 (1) Low Fuel Pressure	The fuel pressure after the secondary fuel filter is lower than expected while the engine is running.
5580-18 Engine Filtered Fuel Delivery Absolute Pressure : Low - moderate severity (2)	E198 (2) Low Fuel Pressure	The fuel pressure after the secondary fuel filter is lower than expected while the engine is running.

Probable Causes

Diagnostic Codes and Event Codes
Fuel Level
Vent Port at the Fuel Tank
Fuel Pressure Sensors
Fuel Pressure Regulating Valve
Fuel Priming Pump
Fuel Transfer Pump
Fuel Transfer Pump Pressure Relief Valve

Recommended Actions

Note: The procedure have been listed in order of probability. complete the procedures in the order of the listed test steps.

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check for Codes A. Apply electrical power to the engine. B. Connect Cat® Electronic Technician (ET) to the service tool connector. C. Look for active codes that are associated with the system for the event code.	Codes	Result: An associated code is active. Repair: Troubleshoot any associated codes before continuing with this test. Result: A code is active or logged. Proceed to Test Step 2.
2. Check the Fuel Tank Level A. Remove electrical power from the engine. B. Inspect the fuel level to make sure that the tank level is not too low.	Fuel Level	Result: The fuel level is NOT low. Proceed to Test Step 3. Result: The fuel level is low. Repair: Add fuel to the fuel tank. Proceed to Test Step 12.
3. Check for Fuel Leaks A. Remove electrical power from the engine. B. Inspect the low-pressure fuel system for leaks. C. Check the low-pressure fuel system connections to make sure that the connectors are properly torqued. D. Check the fuel filter drain plug fittings.	Fuel Tank	Result: A fuel leak was found. Repair: Repair the cause of the fuel leak. Replace parts as necessary. Proceed to Test Step 12. Result: There are no fuel leaks. Proceed to Test Step 4.
4. Prime the Fuel System A. Use the manual priming switch to prime the fuel system. Refer to the Original Equipment Manufacturers (OEM) procedure to prime the fuel system.	Fuel System Primed	Result: The fuel system was priming sequence was completed. Proceed to Test Step 5.
5. Check the Fuel Pressure Sensor A. Apply electrical power to the engine. B. Connect to Cat ET. C. Monitor the following parameter in the status screen: - "Fuel Pressure"	Fuel Pressure	Result: The fuel pressure reading is 0 ± 11 kPa (0 ± 2 psi). For an E198 or 5580 code, proceed to Test Step 6. For a 5578 code, proceed to Test Step 9. Result: The fuel pressure reading is NOT 0 ± 11 kPa (0 ± 2 psi). Repair: Replace the fuel pressure sensor. Proceed to Test Step 12.

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Illustration 1	g03810811
Typical Fuel Filter (1) Starting priority valve (2) System pressure regulator

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Table 3
Troubleshooting Test Steps	Values	Results
6. Check the Low-Pressure Fuel System Pressure Regulator A. Remove electrical power from the engine. B. Remove the low-pressure fuel system pressure regulator from the secondary fuel filter auxiliary manifold. Refer to D&A manual for proper procedure. C. Check the low-pressure fuel system pressure regulator by actuating the spool within the cartridge assembly.	Low-Pressure Fuel System Pressure Regulator	Result: The low-pressure fuel system pressure regulator moves freely through the full travel. Reinstall the low-pressure fuel system pressure regulator. Proceed to Test Step 7. Result: The low-pressure fuel system pressure regulator does NOT freely move through the full travel. Repair: Replace the low-pressure fuel system pressure regulator. Proceed to Test Step 12.

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Illustration 2	g03813358
Pressure relief valve

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Table 4
Troubleshooting Test Steps	Values	Results
7. Check the Fuel Transfer Pump Pressure Relief Valve A. Remove electrical power from the engine. B. Remove the fuel transfer pump pressure relief valve from the fuel transfer pump. Refer to D&A manual for proper procedure. C. Check the fuel transfer pump pressure relief valve by actuating the spool within the cartridge assembly.	Fuel Transfer Pump Pressure Relief Valve	Result: The fuel transfer pump pressure relief valve moves freely through the full travel. Reinstall the fuel transfer pump pressure relief valve. Proceed to Test Step 8. Result: The fuel transfer pump pressure relief valve does NOT freely move through the full travel. Repair: Replace the fuel transfer pump pressure relief valve. Proceed to Test Step 12.

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Illustration 3	g03825758
Injector cooling back-pressure regulator (3) Pressure regulator

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Table 5
Troubleshooting Test Steps	Values	Results
8. Check the Injector Backpressure Regulator A. Remove electrical power from the engine. B. Remove Injector backpressure regulator from the low-pressure injector cooling manifold in the fuel cooling rail. Refer to D&A manual for proper procedure. C. Check the Injector backpressure regulator by actuating the spool within the cartridge assembly.	Injector Backpressure Regulator	Result: The Injector backpressure regulator moves freely through the full travel. Reinstall the Injector backpressure regulator. Proceed to Test Step 11. Result: The Injector backpressure regulator does NOT freely move through the full travel. Repair: Replace the Injector backpressure regulator. Proceed to Test Step 12.
9. Check the Starting Priority Valve A. Remove electrical power from the engine. B. Remove the starting priority valve from the secondary fuel filter head. Refer to D&A manual for proper procedure. C. Check the starting priority valve operation by actuating the spool within the cartridge assembly. Note: For starting priority valve location, refer to Illustration 1.	Starting Priority Valve	Result: The starting priority valve moves freely through the full travel. Reinstall the starting priority valve. Proceed to Test Step 10. Result: The starting priority valve does NOT freely move through the full travel. Repair: Replace the starting priority valve. Proceed to Test Step 12.
10. Check the Fuel Transfer Pump Pressure Relief Valve A. Remove electrical power from the engine. B. Remove the fuel transfer pump pressure relief valve from the fuel transfer pump. Refer to D&A manual for proper procedure. C. Check the fuel transfer pump pressure relief valve by actuating the spool within the cartridge assembly. Note: For fuel transfer pump pressure relief valve location, refer to Illustration 2.	Fuel Transfer Pump Pressure Relief Valve	Result: The fuel transfer pump pressure relief valve moves freely through the full travel. Reinstall the fuel transfer pump pressure relief valve. Proceed to Test Step 11. Result: The fuel transfer pump pressure relief valve does NOT freely move through the full travel. Repair: Replace the fuel transfer pump pressure relief valve. Proceed to Test Step 12.
11. Replace the Fuel Transfer Pump A. Remove electrical power from the engine. B. Replace the fuel transfer pump.	Fuel Transfer Pump	Result: The transfer pump was replaced. Proceed to Test Step 12.
12. Check for Codes A. Start the engine and operate at high idle for 1 minute. B. Look for active or logged diagnostic codes.	Diagnostic Codes	Result: No codes present. Return 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).