C175 Tier 4 Final Engines for Off-Highway Trucks Caterpillar

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

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.

Table 2

Associated Codes
J1939 Code	CDL Code	Troubleshooting Procedure
95-0	E390 (3)	Troubleshooting, "Fuel Filter Is Restricted"
95-15	E390 (1)	Troubleshooting, "Fuel Filter Is Restricted"
95-16	E390 (2)	Troubleshooting, "Fuel Filter Is Restricted"
1381-17	E2172 (1)	Troubleshooting, "Fuel Transfer Pump Inlet Pressure Is Low"
1382-15	E1129 (1)	Troubleshooting, "Fuel Filter Is Restricted"
1382-16	E1129 (2)	Troubleshooting, "Fuel Filter Is Restricted"
5417-15	E1569 (1)	Troubleshooting, "Clean Fuel Module - Test"
5417-16	E1569 (2)	Troubleshooting, "Clean Fuel Module - Test"

Table 3

Troubleshooting Test Steps	Values	Results
1. Check for Codes A. Turn the keyswitch to ON. 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. Turn the keyswitch to OFF. B. Inspect the fuel level to make sure that the tank level is not too low.	Fuel Level	Result: The fuel level is OK. Proceed to Test Step 3. Result: The fuel level is NOT OK. Repair: Add fuel to the fuel tank. Proceed to Test Step 13.
3. Check for Fuel Leaks A. Turn the keyswitch to OFF. 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.	Fuel Tank	Result: A fuel leak was found. Repair: Repair the cause of the fuel leak. Replace parts as necessary. Proceed to Test Step 13. 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 Operation and Maintenance Manual, "Fuel System - Prime" for the correct procedure.	Fuel System Primed	Result: The fuel system priming sequence was completed. Proceed to Test Step 5.
5. Check the Fuel Pressure Sensor A. Turn the keyswitch to ON. 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). Repair: 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 13.

Illustration 1	g06101717
(1) Starting priority valve (2) Low-pressure fuel system pressure regulator

Table 4

Troubleshooting Test Steps	Values	Results
6. Check the Low-Pressure Fuel System Pressure Regulator A. Turn the keyswitch to OFF. B. Remove the low-pressure fuel system pressure regulator from the secondary fuel filter auxiliary manifold. Refer to the Disassembly and Assembly 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 is OK. Repair: Reinstall the low-pressure fuel system pressure regulator. Proceed to Test Step 7. Result: The low-pressure fuel system pressure regulator is NOT OK. Repair: Replace the low-pressure fuel system pressure regulator. Proceed to Test Step 13.

Illustration 2	g06101760
(3) Low-pressure fuel system pressure relief valve

Table 5

Troubleshooting Test Steps	Values	Results
7. Check the Fuel Transfer Pump Pressure Relief Valve A. Turn the keyswitch to OFF. B. Remove the fuel transfer pump pressure relief valve from the fuel transfer pump. Refer to the Disassembly and Assembly 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 is OK. Repair: Reinstall the fuel transfer pump pressure relief valve. Proceed to Test Step 8. Result: The fuel transfer pump pressure relief valve is NOT OK. Repair: Replace the fuel transfer pump pressure relief valve. Proceed to Test Step 13.

Illustration 3	g06101746
(4) Injector cooling back-pressure regulator

Table 6

Troubleshooting Test Steps	Values	Results
8. Check the Injector Back-pressure Regulator A. Turn the keyswitch to OFF. B. Remove injector back-pressure regulator from the low-pressure injector cooling manifold in the fuel cooling rail. Refer to the Disassembly and Assembly manual for proper procedure. C. Check the injector back-pressure regulator by actuating the spool within the cartridge assembly.	Injector Back-pressure Regulator	Result: The injector back-pressure regulator is OK. Repair: Reinstall the Injector back-pressure regulator. Proceed to Test Step 12. Result: The injector back-pressure regulator is NOT OK. Repair: Replace the Injector back-pressure regulator. Proceed to Test Step 13.

Illustration 4	g06297294
Priming pump bypass valve (5) Internal bypass valve

Table 7

Troubleshooting Test Steps	Values	Results
9. Check the Priming Pump Bypass Valve A. Turn the keyswitch to OFF. B. Remove the priming pump bypass valve from the priming pump housing. Refer to the Disassembly and Assembly manual for proper procedure. C. Remove the priming pump bypass valve from the cooling recirculation block. D. Check the fuel priming pump bypass valve by actuating the spool within the cartridge assembly.	Priming Pump Bypass Valve	Result: The fuel priming pump bypass valve is OK. Repair: Reinstall the fuel priming pump bypass valve. Proceed to Test Step 10. Result: The fuel priming pump bypass valve is NOT OK. Repair: Replace the fuel priming pump bypass valve. Proceed to Test Step 13.
10. Check the Starting Priority Valve A. Turn the keyswitch to OFF. B. Remove the starting priority valve from the secondary fuel filter head. Refer to the Disassembly and Assembly 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 is OK. Repair: Reinstall the starting priority valve. Proceed to Test Step 11. Result: The starting priority valve is NOT OK. Repair: Replace the starting priority valve. Proceed to Test Step 13.
11. Check the Fuel Transfer Pump Pressure Relief Valve A. Turn the keyswitch to OFF. B. Remove the fuel transfer pump pressure relief valve from the fuel transfer pump. Refer to the Disassembly and Assembly 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 is OK. Reinstall the fuel transfer pump pressure relief valve. Proceed to Test Step 12. Result: The fuel transfer pump pressure relief valve is NOT OK. Repair: Replace the fuel transfer pump pressure relief valve. Proceed to Test Step 13.
12. Replace the Fuel Transfer Pump A. Turn the keyswitch to OFF. B. Replace the fuel transfer pump.	Fuel Transfer Pump	Result: The transfer pump was replaced. Proceed to Test Step 13.
13. 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).