CORE ASSEM. 4L7908 - Caterpillar

Use this procedure in order to troubleshoot a problem with low fuel pressure. Also, use this procedure if one of the following diagnostic codes is active or easily repeated.
Table 1
Diagnostic Codes Table    
J1939 Code and Description    Conditions which Generate this Code    System Response    
5580-17
Engine Filtered Fuel Delivery Pressure (After Secondary Filter Gauge): Low - least severe (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)    Probable Causes
Diagnostic codes
Fuel tank
Fuel leaks and fuel filters
Fuel transfer pump
Fuel pressure sensor
Fuel return pressure regulatorRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in the order of the listed test steps.
Table 2
Troubleshooting Test Steps    Values    Results    
1. Check for Active Codes and Logged 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 code is active or logged.
Repair: Troubleshoot any codes before continuing with this procedure.
Verify that the repair eliminated the problem.
Result: A code is not active or logged.
Proceed to Test Step 2.
   
2. Check the Fuel Tank Level
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 Level
   
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.
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: