0438276 JOHNSON CARBURETOR ASSY.

Probable Causes
Active codes
Oil in the exhaust system
Cold mode operation (if applicable). Refer to "Cold Mode Operation" within the Systems Operation, "General Information".
Starting aids (if applicable)
Noncurrent flash file
Cooling system
Unstable fuel supply
Unstable fuel injectionRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in order.
Table 1
Troubleshooting Test Steps Values Results
1. Active Codes and Logged Codes
A. Establish communication between Caterpillar Electronic Technician (ET) and the Electronic Control Module (ECM) . Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Determine if a code is active or logged.
Diagnostic code
Result: A code is active or logged.
Troubleshoot any active codes before continuing with this procedure.
Result: A code is not active or logged.
Proceed to Test Step 2.
2. Oil in the Exhaust System
A. Check for oil in the exhaust system.
Oil in the exhaust system
Result: The exhaust system contains oil.
Determine the cause of oil in the exhaust system and make the necessary repairs.
Proceed to Test Step 3.
Result: The exhaust system does not contain oil.
Proceed to Test Step 4.
3. Clean Oil from the Exhaust System
A. Remove excess oil from piping with a clean cloth.
B. Operate the engine at elevated idle (1500 RPM) for 10 minutes.
Oil in the exhaust system
Result: Oil has been cleaned from the exhaust system and the white smoke has dissipated.
Return the unit to service.
Result: Oil has been cleaned from the exhaust system but the white smoke did not dissipate.
Proceed to Test Step 4.
4. Cold Mode Operation (if applicable)
During cold mode operation, condensation may be present and is normal.
A. Cold mode is activated whenever the engine coolant temperature falls below a predetermined value. Monitor the status screen on Cat ET in order to verify that the engine has exited cold mode. Observe the reading for coolant temperature on the Cat ET.
Cold mode
Result: The engine is operating in cold mode.
This is normal operation. Return the engine to service.
Result: The engine is not operating in cold mode.
Proceed to Test Step 5.
5. Starting Aids (If Applicable)
A. If cold ambient conditions exist, check operation of starting aids. Verify that the starting aid is operating correctly. Refer to the appropriate circuit test for information that is related to troubleshooting the starting aid.
If ether bottles are not installed, check the configuration screen on Cat ET in order to verify that ether is not enabled.
Starting aid
Result: The starting aid is operating correctly.
Proceed to Test Step 6.
Result: The starting aid is not operating correctly.
Make the necessary repairs. Verify that the repair corrected the problem.
6. Noncurrent Flash File
A. Verify that the latest flash file is installed in the ECM. Refer to Troubleshooting, "ECM Software - Install" for the proper procedure.
Flash file
Result: The latest flash file is installed.
Proceed to Test Step 7.
Result: The latest flash file is not installed.
Install the latest flash file. Verify that the repair eliminates the problem.
7. Cooling System
A. Check for an internal coolant leak into the cylinder and/or the exhaust. Refer to Systems Operation/Testing and Adjusting, "Cooling System".
Internal coolant leak
Result: There is an internal coolant leak.
Make the necessary repairs. Verify that the repair eliminated the problem.
Result: There is not an internal coolant leak.
Proceed to Test Step 8.
8. Unstable Fuel Supply
A. Visually check the fuel level in the fuel tank. Do not rely on the fuel gauge only.
B. Ensure that the fuel supply valve (if equipped) is in the full OPEN position.
C. Inspect the fuel system. Refer to Systems Operation/Testing and Adjusting, "Fuel System - Inspect" for additional information.
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.
D. Check fuel quality. Check the fuel tank for debris or foreign objects which may block the fuel supply.
E. Check the filtered fuel pressure while the engine is being cranked. Refer to Troubleshooting, "Fuel Pressure Is Low" for the proper testing procedure.
Fuel system
Result: The fuel system is operating properly.
Proceed to Test Step 9.
Result: The fuel system is not operating properly.
Make the necessary repairs. Verify that the repair eliminates the problem.
9. Fuel Injectors
If service has been performed on the engine fuel system recently, verify that the injector trim files are correct. Use Cat ET to check that the injector trim files are correct for the injectors that are installed on the engine.
C13, C15, and C18 Applications
A. Perform the "Injector Solenoid Test" on Cat ET in order to determine if all of the injector solenoids are being energized by the ECM.
B. Access the "Cylinder Cutout Test" in the "Diagnostic Tests" under the "Diagnostics" menu.
C. Perform the "Automatic Cylinder Cutout Test" on Cat ET.
C9.3 Applications
A. Use Cat ET to ensure that there are not any active diagnostic codes for the injector solenoids. Perform the "Cylinder Cutout Test" in order to check for a misfiring cylinder. Refer to Troubleshooting, "Injector Solenoid - Test" for information that is related to the test.
Use Cat ET to perform the "Fuel System Verification Test" in order to check the mechanical condition of the fuel injectors. Refer to Troubleshooting, "Injector Solenoid - Test" for information that is related to the test.
Injector Solenoid Test or Fuel System Verification Test
Result: The test was successful.
Return the unit to service.
Result: The test was not successful.
Diagnose the problem and then repair the problem.
Reset all active codes and clear all logged codes.
Verify that the repair eliminated the problem.
Complete the procedure in the order in which the steps are listed.The procedure corrected the issue. Return the engine to service.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).