C175-16 Locomotive Engine Caterpillar

Fuel Pressure Is Low

Usage:

Use this procedure to troubleshoot a problem with low fuel pressure. Also, use this procedure if one of the following event codes is active or logged.

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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.

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Table 2
Associated Codes
J1939 Code	CDL Code	Troubleshooting Procedure
1381-17	E2172 (1)	Troubleshooting, "Fuel Transfer Pump Inlet Pressure Is Low"
5584-0	E390 (3)	Troubleshooting, "Fuel Filter Is Restricted"
5584-15	E390 (1)	Troubleshooting, "Fuel Filter Is Restricted"
5584-16	E390 (2)	Troubleshooting, "Fuel Filter Is Restricted"

Probable Causes

Codes
Fuel level
Leaks
Voltage
Sensor
Low-pressure regulator
Relief valve
Back-pressure regulator
Bypass valve
Starting priority valve

Recommended Actions

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Table 3
Troubleshooting Test Steps	Values	Results
1. Check for Codes A. Connect Cat^® Electronic Technician (ET) to the service tool connector. B. 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 14.
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. E. Check for air in the fuel. Refer to Testing and Adjusting, "Air in Fuel - Test" for the proper procedure.	Leaks	Result: A fuel leak was found. Repair: Repair or replace damaged fuel system components. Proceed to Test Step 14. Result: There are no fuel leaks. Proceed to Test Step 4.
4. Check for Power to the Low-Pressure Fuel Supply Pump A. Turn the keyswitch to OFF. B. Disconnect the wiring harness from the low-pressure fuel supply pump. C. Turn the keyswitch to ON. D. Connect Cat ET. E. Use Cat ET to perform the following override: - "Electric Fuel Transfer Pump Relay Override" F. Measure the voltage between the following pins on the wiring harness connector for the low-pressure fuel supply pump: - Pin 2 and Pin 3 - Pin 2 and Pin 4 G. Inspect and clean the fuel supply clean.	Voltage	Result: The voltage at the low-pressure fuel supply pump module connector is equal to system voltage. Proceed to Test Step 5. Result: The voltage at the low-pressure fuel supply pump module connector is NOT equal to system voltage. Repair: There is a problem with the power supply circuit between the low-pressure fuel supply pump connector and the battery supply. Check the circuit protection device, low-pressure fuel supply pump relay, and the ground for the low-pressure fuel supply pump circuit. Refer to the appropriate wiring diagram to troubleshoot the circuit. Proceed to Test Step 5.
5. Prime the Fuel System A. Prime the fuel system. Refer to Operation and Maintenance Manual, "Fuel System - Prime" for the additional information.	Fuel System	Result: The fuel system priming sequence was completed. Proceed to Test Step 6.
6. Check the Fuel Pressure Sensor A. Connect Cat ET. B. Use Cat ET to monitor the following parameter in the status screen: - "Fuel Pressure"	Sensor	Result: The fuel pressure reading is 0 ± 11 kPa (0 ± 2 psi). For an E198 or 5580 code, proceed to Test Step 7. For a 5578 code, proceed to Test Step 10. Result: The fuel pressure reading is NOT 0 ± 11 kPa (0 ± 2 psi). Repair: Replace the fuel pressure sensor. Proceed to Test Step 14.

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Illustration 1	g06307940
(1) Starting priority valve (2) Low-pressure system regulator (3) Priming loop check valve

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Table 4
Troubleshooting Test Steps	Values	Results
7. 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 the Disassembly and Assembly manual for additional information. C. Check the low-pressure fuel system pressure regulator by actuating the spool within the cartridge assembly.	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 8. 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 14.

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Illustration 2	g03813358
Pressure relief valve

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Table 5
Troubleshooting Test Steps	Values	Results
8. 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 the Disassembly and Assembly manual for additional information. C. Check the fuel transfer pump pressure relief valve by actuating the spool within the cartridge assembly.	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 9. 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 14.

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Illustration 3	g06307994
(4) Injector back-pressure regulator

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Table 6
Troubleshooting Test Steps	Values	Results
9. Check the Injector Back-pressure 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 the Disassembly and Assembly manual for additional information. C. Check the Injector back-pressure regulator by actuating the spool within the cartridge assembly.	Back-pressure Regulator	Result: The Injector back-pressure regulator moves freely through the full travel. Reinstall the Injector back-pressure regulator. Proceed to Test Step 13. Result: The Injector back-pressure regulator does NOT freely move through the full travel. Repair: Replace the Injector back-pressure regulator. Proceed to Test Step 14.
10. Check the Low-Pressure Fuel Pump Bypass Valve A. Remove electrical power from the engine. B. Remove the low-pressure fuel pump bypass valve from the priming pump housing. Refer to the Disassembly and Assembly manual for additional information. C. Check the low-pressure fuel pump bypass valve by actuating the spool within the cartridge assembly.	Bypass Valve	Result: The low-pressure fuel pump bypass valve moves freely through the full travel. Reinstall the fuel priming pump bypass valve. Proceed to Test Step 11. Result: The low-pressure fuel pump bypass valve does NOT freely move through the full travel. Repair: Replace the low-pressure fuel pump bypass valve. Proceed to Test Step 14.
11. 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 the Disassembly and Assembly manual for additional information. 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.	Priority Valve	Result: The starting priority valve moves freely through the full travel. Reinstall the starting priority valve. Proceed to Test Step 12. Result: The starting priority valve does NOT freely move through the full travel. Repair: Replace the starting priority valve. Proceed to Test Step 14.
12. 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 the Disassembly and Assembly manual for additional information. 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.	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 13. 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 14.
13. 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 14.
14. Check for Codes A. Start the engine. B. Run the engine until normal operating temperature has been reached. C. Bring the engine to high idle for 1 minute. D. Connect Cat ET. E. Use Cat ET to monitor the following: - Codes.	Codes	Result: A code is not active. 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).