PLATE 8J7978 - Caterpillar

Use this procedure to troubleshoot a problem with high fuel pressure. Also, use this procedure if one of the following event codes is active or logged.
Table 1
J1939 Code and Description CDL Code and Description Comments
94-0
Engine Fuel Delivery Pressure : High - most severe (3) E1218 (3)
High Unfiltered Fuel Pressure The code is logged.
94-15
Engine Fuel Delivery Pressure : High - least severe (1) E1218 (1)
High Unfiltered Fuel Pressure The code is logged.
94-16
Engine Fuel Delivery Pressure : High - moderate severity (2) E1218 (2)
High Unfiltered Fuel Pressure The code is logged. Probable Causes
Codes
Sensor
Fuel lines
Transfer pump
Pressure regulatorRecommended Actions
Table 2
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 Pressure Sensor
A. Connect Cat ET.
B. Use Cat ET to monitor the following pressure:
- Fuel pressure
C. Use a mechanical gauge to check the system fuel pressure. Refer to Systems Operation/Testing and Adjusting, "Fuel Pressure" for additional information.
Note: If a mechanical gauge is not available, determine if the fuel pressure reading on Cat ET is reasonable.
Sensor
Result: The gauge value of the fuel pressure is reasonable when compared to the fuel pressure reading shown in Cat ET.
Proceed to Test Step 3.
Result: The gauge value of the fuel pressure is not reasonable when compared to the fuel pressure reading shown in Cat ET.
Repair: Replace the pressure sensor. Reset all active codes and clear all logged codes by cycling the keyswitch to the Off position.
If the problem is not resolved, proceed to Test Step 3.
3. Inspect the Fuel Lines
A. Visually inspect the fuel lines. Also, inspect the fuel cooler, if equipped.
B. Inspect the fuel lines for the following:
- Restrictions
- Pinching
- Swelling
Fuel Lines
Result: The fuel lines and the cooler (if equipped) are OK.
Proceed to Test Step 4.
Result: The fuel lines and the cooler (if equipped) are NOT OK.
Repair: Make the necessary repairs. Reset all active codes and clear all logged codes by cycling the keyswitch to the Off position.
If the problem is not resolved, proceed to Test Step 4.
4. Replace the Fuel Pressure Regulator
Pressure Regulator
Result: The regulator was replaced. Reset all active codes and clear all logged codes by cycling the keyswitch to the Off position.
If the problem is not resolved, proceed to Test Step 5.
5. Inspect the Relief Valve for the Transfer Pump
Note: The spring must move freely.
Relief Valve
Result: The relief valve is stuck closed.
Repair: Replace the fuel transfer pump. Reset all active codes and clear all logged codes by cycling the keyswitch to the Off position.
Verify that the repair eliminated the problem.
Result: The relief valve is OK.
Clean the relief valve and reinstall the relief valve. Reset all active codes and clear all logged codes by cycling the keyswitch to the Off position.
Verify that the repair eliminated the problem.
If the procedure did not correct the issue, contact your Cat