0174679 JOHNSON TRIM GAUGE ASSY.

Probable Causes
Seals
Fuel injector
Fuel transfer pump
High-pressure fuel pump
Cylinder headRecommended Actions
Table 1
Troubleshooting Test Steps Values Results
1. Check for Leaking Injector O-ring Seals
A. Remove the injector from the affected cylinder and visually inspect the injector O-ring seals for damage.
B. If the leakage is not located, add the appropriate dye to the fuel tanks.
a. Run the engine at high idle for several minutes.
b. Shut down the engine and remove the valve covers.
c. Use a black light to check for traces of dye around each injector.
O-ring Seal
Result: The fuel injector O-ring seal is not damaged.
Proceed to Test Step 2.
Result: The fuel injector O-ring seal is damaged.
Repair: Replace the damaged seals.
If the problem is not resolved, proceed to Test Step 2.
2. Inspect the Fuel Injector Tip
A. Connect Cat® Electronic Technician (ET) to the service tool connector.
B. Use Cat ET to perform the following fuel injector test:
- "Cylinder Cutout Test"
Note: A fuel injector tip that is broken or fractured is a possible cause of a cylinder that is being overfueled.
C. If a cylinder is identified by the test, Remove the injector and check the injector tip for damage. Check the fuel injector tip for cracks or breakage.
Injector Tip
Result: The fuel injector tip is not damaged.
Proceed to Test Step 3.
Result: The fuel injector tip is damaged.
Repair: Replace damaged fuel injector. Refer to Troubleshooting, "Injector Trim File - Install" and Troubleshooting, "Injector Solenoid - Test" for additional information.
If the problem is not resolved, proceed to Test Step 3.
3. Inspect the Fuel Transfer Pump Seal
A. Check for fuel leakage around the shaft seal for the fuel transfer pump.
B. Ensure that the weep hole is not plugged.
Pump Seal
Result: There is not fuel leakage around the shaft seal.
Proceed to Test Step 4.
Result: There is fuel leakage around the shaft seal.
Repair: Replace the fuel transfer pump.
If the problem is not resolved, proceed to Test Step 4.
4. Check the High-Pressure Fuel Pump
Note: Perform this test on a cold engine.
Note: Verify the "Fuel Rail Pressure" reading in Cat ET is 0 8 MPa (1160 psi) prior to servicing the fuel system. Refer to Testing and Adjusting, "Fuel Rail Pressure - Release" for instructions on how to release the pressurized fuel.
A. Remove plug (1) from the bottom of the fuel pump. Expect engine oil will drain from the opening. Check the magnetic plug for debris.
B. Connect Cat (ET).
C. Use Cat ET to perform the following override to pressurize the fuel system:
- "Fuel Pump Relay Command Override"
Note: Allow the pump to run for at least 5 minutes while you monitor the drain hole in the fuel pump adapter for leakage.
Note: If a manual switch is not available, use the override in Cat ET to operate the fuel priming pump. For a pump that is in good repair, fuel may drip intermittently from the adapter drain hole. The leakage must not exceed 6 mL/min (0.2 oz/min).
D. Use Cat ET to turn off the following override:
- "Fuel Pump Relay Command Override"
E. Clean the magnetic drain plug and reinstall the drain plug into the pump.
Pump
Result: The leakage was less than 6 mL/min (0.2 oz/min).
If the problem is not resolved, proceed to Test Step 5.
Result: The leakage was more than 6 mL/min (0.2 oz/min).
Repair: A failed high-pressure fuel pump has been detected. Repair or Replace the high-pressure fuel pump.
Verify that the repair eliminated the problem. Return to service.
5. Check for a Cracked Cylinder Head
A. Look for signs of damage to the internal passages for the fuel supply to the injectors in the cylinder head. Check for pin hole leaks. Refer to the Disassembly and Assembly manual for additional information.
Cracked Head
Result: The internal passages for the fuel supply to the injectors are damaged.
Repair: Repair or replace the cylinder head.
Verify that the repair eliminated the problem.
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).