C9.3 Engines for Caterpillar Built Machines Fuel Pressure Is Low Caterpillar

Fuel Pressure Is Low

C9.3 Engines for Caterpillar Built Machines [KENR5393]

C9.3 Engines for Caterpillar Built Machines Fuel Pressure Is High

C9.3 Engines for Caterpillar Built Machines Sensor Supply - Test

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C9.3 Engines for Caterpillar Built Machines Fuel Pressure Is High

1.1. Probable Causes

System Operation Description:

Probable Causes

Fuel
Fuel Tank
Fuel Filters
Fuel Transfer Pump
Fuel Pressure Sensor
Fuel Return Pressure Regulator
Anti-Drain Check Valve
Fuel Lines

Use this procedure in order to troubleshoot a low fuel pressure. 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".

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Table 1
Event Code
CDL Code	Code Description	Comments
E198 (1)	Low Fuel Pressure	The code is logged.
E198 (2)	Low Fuel Pressure	The engine power is derated. The code is logged. The ECM will illuminate the action lamp.

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check for Codes A. Connect Cat ET to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools", if necessary. B. Determine if a diagnostic trouble code is present.	Codes	Result: A E198 code is present. Proceed to test Step 2. Result: A code other than a E198 code is present. Repair: Troubleshoot the code. Refer to the proper troubleshooting procedure. Low fuel pressures may cause high fuel temperatures. Troubleshoot a code for low fuel pressure before troubleshooting a code for high fuel temperature. STOP
2. Check the Fuel Level in the Tank A. Remove the fuel tank cap from the fuel tank. Check the vent port that is in the cap for debris. Clear any restrictions with compressed air. B. Visually inspect the fuel level in the fuel tank. Ensure that the fuel tank contains enough fuel in order to operate the engine. C. Ensure that the fuel supply valve (if equipped) is in the full OPEN position.	Fuel Level	Result: The fuel level is OK. Proceed to Test Step 3. Result: The fuel level is NOT OK. Repair: Fill the tank. If the problem is not resolved, proceed to Test Step 3.
3. Inspect the Fuel System for Leaks A. Perform a visual inspection of the fuel system. Verify that there are no fuel leaks. Inspect the fuel lines from the fuel transfer pump to the secondary fuel filter base for restrictions. Note: Cold weather adversely affects the characteristics of the fuel. Refer to the engines Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold-weather operation.	Leaks	Result: No leaks were found. Proceed to Test Step 4. Result: Leaks were found in the fuel system. If the problem is not resolved, proceed to Test Step 4.

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Table 3
Required Tooling
8T-7860 Connector
110-6349 Fitting as
8T-0855 Pressure Gauge
6V-3990 Coupler

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Illustration 1	g02023390
(1) Fuel temperature sensor (2) Fuel sampling port (3) Fuel pressure sensor (4) Fuel filter base

Note: Do not use the fuel sampling port (2) for measuring the pressure. Follow the steps below.

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Table 4
Engine RPM	Fuel pressure from Cat ET	Fuel pressure from the mechanical gauge
800
1800

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Table 5
Troubleshooting Test Steps	Values	Results
4. Check the Fuel Pressure Sensor A. Record the fuel pressure from Cat ET. Record the data in Table 4. B. Remove the fuel pressure sensor (3). C. Install a 8T-7860 Connector into the port of the pressure sensor (3). D. Install the 110-6349 Fitting as onto the 8T-7860 Connector. E. Install a 8T-0855 Pressure Gauge onto a 6V-3990 Coupler. F. Install the 6V-3990 Coupler onto the 110-6349 Fitting as. G. Record the fuel pressure on the pressure gauge. Record the data in Table 4.	Fuel Pressure Sensor	Result: The gauge value of the fuel pressure is within 137 kPa (20 psi) of the fuel pressure reading shown in ET. Proceed to Test Step 5. Result: The gauge value of the fuel pressure is not within 137 kPa (20 psi) of the fuel pressure reading shown in ET. Repair: Replace the fuel pressure sensor. If the problem is not resolved, proceed to Test Step 5.

Verify that the recorded fuel pressure is above the minimum acceptable fuel specifications. Refer to Table 6 for the minimum acceptable specifications.

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Table 6
Engine RPM	Minimum acceptable fuel pressure
800	360 kPa (52 psi)
1800	450 kPa (65 psi)

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Table 7
Troubleshooting Test Steps	Values	Results
5. Verify that the Fuel Pressure Is Within Specifications	Fuel Pressure	Result: The fuel pressure is above the minimum acceptable fuel specifications. Proceed to Test Step 7. Result: The fuel pressure is not above the minimum acceptable fuel specifications. Proceed to Test Step 6.
6. Replace the Fuel Filters A. Replace the primary filter, the secondary filter, and the tertiary fuel filters. Note: The fuel system will need to be primed after the filters are replaced. B. Verify that the fuel pressure is above the minimum acceptable pressure specifications. Refer to Table 6 for the proper specifications.	Fuel Filters	Result: The fuel pressure meets the minimum acceptable fuel pressure specifications. Return the engine to service. STOP Result: The fuel pressure does not meet the minimum acceptable fuel pressure specifications. Proceed to Test Step 7.
7. Check for Air in the Fuel System A. Check for air in the fuel. Refer to Systems Operation/Testing and Adjusting, "Air in Fuel - Test" for the proper procedure.	Air	Result: Air is in the system. Repair: Refer to Systems Operation/Testing and Adjusting, "Air in Fuel - Test" for the proper repairs. If the problem is not resolved, proceed to Test Step 8. Result: Air is not in the system. Proceed to Test Step 8.

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Illustration 2	g02025071
(5) Anti-drain check valve (6) Fuel return pressure regulator

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Contact with high pressure fuel may cause fluid penetration and burn hazards. High pressure fuel spray may cause a fire hazard. Failure to follow these inspection, maintenance and service instructions may cause personal injury or death.

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Table 8
Troubleshooting Test Steps	Values	Results
8. Replace the Fuel Return Pressure Regulator A. Replace the fuel return pressure regulator. B. Inspect the anti-drain check valve for proper operation. C. Check the fuel pressure with Cat ET. Note: Refer to Table 6 for the proper specifications.	Pressure Regulator	Result: The fuel pressure meets the minimum acceptable fuel pressure specifications. Return the engine to service. STOP Result: The fuel pressure does not meet the minimum acceptable fuel pressure specifications. Proceed to Test Step 9.
9. Inspect the Relief Valve of the Transfer Pump A. Inspect the relief valve for the transfer pump. The spring must move freely.	Relief Valve	Result: The relief valve is stuck open. Repair: Replace the fuel transfer pump. Verify that the problem has been resolved. STOP Result: The relief valve is OK. Clean the relief valve and reinstall the relief valve. Proceed to Test Step 10.
10. Perform a Pump Lift Test	Pump Lift Test	Result: The pump failed the pump lift test. Repair: Replace the transfer pump. Verify that the problem has been resolved. STOP

Test Step 1.

The procedure corrected the issue.

Results:

The procedure did not correct the issue. -
Repair: Contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).

STOP