3512C and 3516C Marine Auxiliary Engines Caterpillar

Fuel Pressure Is Low

Usage:

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

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Table 1
Engine Event
J1939 Code and Description	Conditions that Generate the Code	System Response
5580-17 Engine Filtered Fuel Delivery Pressure (After Secondary Filter Gauge): Low - least severity (1)	The fuel pressure has dropped below trip point for the specified delay time.	The code is logged.
5580-18 Engine Filtered Fuel Delivery Pressure (After Secondary Filter Gauge): Low - moderate severity (2)		The code is logged.

Probable Causes

Diagnostic codes
Fuel tank
Fuel leaks and fuel filters
Fuel Transfer Pump
Fuel Pressure Sensor
Fuel Return Pressure Regulator

Recommended Actions

Note: The procedures 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. Diagnostic Codes A. Connect Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools", if necessary. B. Monitor the diagnostic codes on Cat ET. Check for active or logged diagnostic codes. Specifically check for codes that could be associated to low fuel pressure. Note: Wait at least 30 seconds in order for diagnostic codes to become active.	Codes	Result: A diagnostic code is present. Repair: Troubleshoot any codes before continuing with this procedure. Verify that the repair eliminated the problem. Result: A diagnostic code is not present. Proceed to Test Step 2.
2. Check the Fuel Tank A. Visually inspect the fuel level in the fuel tank. Ensure that the fuel tank contains enough fuel in order to operate the engine. B. Ensure that the fuel supply valve (if equipped) is in the full OPEN position. C. Check the vent port that is at the fuel tank for debris. Note: Do not allow debris to enter the fuel tank while you clean the cap. Damage to the fuel system will occur.	Fuel Tank	Result: The fuel level is OK. Proceed to Test Step 3. Result: The fuel level is not OK. Repair: Fill the tank. Verify that the repair eliminated the problem.
3. Inspect the Fuel System for Leaks A. Perform a visual inspection of the fuel system. Verify that there are no fuel leaks or restrictions.	Fuel system leaks	Result: No leaks or restrictions were found. Repair: Replace the fuel filters and prime the fuel system. Verify that the repair eliminated the problem. If the problem is not resolved, proceed to Test Step 4. Result: Leaks or restrictions were found in the fuel system. Repair: Repair the leaks. Verify that the repair eliminated the problem.
4. Check the Fuel Pressure Sensor A. Start the engine. Run the engine at low idle. Use Cat ET to monitor the fuel pressure for the engine. B. Check the value of the parameter while the engine is at low idle. Ensure that the value of the parameter is reasonable. C. Increase the engine speed while you monitor the parameter. Ensure that the value of the parameter increases with engine speed. Ensure that the value of the sensor remains reasonable as the pressure is increased.	Fuel Pressure Sensor	Result: The value of the fuel pressure is reasonable. Proceed to Test Step 5. Result: The value of the fuel pressure is not reasonable. Repair: Replace the pressure sensor. Verify that the repair eliminated the problem.
5. Pressure Regulator A. Clean any contamination or debris that may keep the regulating valve open. Check the regulator for damage. B. If the fuel pressure is not within specifications, adjust the regulator. Refer to System Operation Testing and Adjusting, "Fuel Pressure". If a problem with the regulator is suspected, replace the fuel pressure regulator.	Pressure Regulator	Result: The pressure is within specifications. Proceed to Test Step 6. Result: The pressure is not within specifications. Repair: Adjust or replace the pressure regulator. Verify that the repair eliminated the problem.
6. Replace the Transfer Pump A. Start the engine. If the fuel pressure decreases after starting the engine, replace the fuel transfer pump.	Transfer Pump	Result: The transfer pump was replaced. Verify that the repair eliminated the problem.