0432125 JOHNSON CARB. ASSY., 100STL models

Probable Causes
Diagnostic codes
Fuel pump calibration
Accessory and/or parasitic loads
Throttle signal for the throttle position sensor (if equipped)
Throttle signal for the CAN data link (if equipped)
Air intake and exhaust system
Fuel supply
Fuel system cleaning required
Low compression (cylinder pressure)
Electronic unit injectors
Individual malfunctioning cylindersRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in order.
Table 1
Troubleshooting Test Steps Values Results
1. Diagnostic Codes
A. Establish communication between the electronic service tool and the Electronic Control Module (ECM). Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Download the Product Status Report before troubleshooting or clearing any diagnostic codes.
Note: The downloaded information will be required by the DSN if troubleshooting assistance is needed.
C. Use the electronic service tool to check for active or logged codes.
Diagnostic codes
Result: There are active or logged codes.
Repair: Troubleshoot any codes before continuing with this procedure.
Result: There are no active or logged codes.
Proceed to Test Step 2.
2. Fuel Pump Calibration
A. Establish communication between the electronic service tool and the Electronic Control Module (ECM). Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Perform the "Fuel Pump Learn" procedure.
Fuel pump calibration
Result: The symptom is eliminated.
Repair: Return the unit to service.
Result: The symptom is still present.
Proceed to Test Step 3.
3. Accessory and/or Parasitic Loads
A. Check all accessory equipment for problems that may create excessive load on the engine.
B. Check for any excess parasitic load on the engine.
Parasitic loads
Result: There is an excessive load on the engine.
Repair: Diagnose and repair the fault.
Verify that the repair eliminated the fault.
Result: There is not an excessive load on the engine.
Proceed to Test Step 4.
4. Throttle Signal for the Throttle Position Sensor (If Equipped)
A. Use the electronic service tool and observe the signal for the throttle position sensor. Make sure that the throttle reaches the 100% raw position and the calibrated position.
Analog throttle input
Result: The throttle signal is erratic or does not reach the 100% raw position or the calibrated position.
Repair: Refer to Troubleshooting, "Speed Control (Analog) - Test".
Result: The throttle signal is OK.
Proceed to Test Step 5.
5. Throttle Signal for the CAN Data Link (If Equipped)
A. Use the electronic service tool and observe the signal for the throttle position sensor. Make sure that the throttle reaches the 100% raw position and the calibrated position.
CAN data link
Result: The throttle signal is erratic or does not reach the 100% raw position or the calibrated position.
Repair: Refer to Troubleshooting, "CAN Data Link - Test".
Result: The throttle signal is OK.
Proceed to Test Step 6.
6. Air Intake and Exhaust System
A. Check the air filter restriction indicator, if equipped.
B. Check the air inlet and exhaust system for restrictions and/or leaks.
C. Check for ECM codes for inlet air restriction:
107-15: Engine Air Filter 1 Differential Pressure high - least severe (1)
107-16: Engine Air Filter 1 Differential Pressure high - moderate severity (2)
Restrictions
Result: The air filter is plugged.
Repair: Clean or replace the air filter. Refer to the Operation and Maintenance Manual for further information.
Result: There are restrictions in the air inlet or exhaust system.
Repair: Make the necessary repairs, Verify that the repair eliminated the fault.
Result: A 107-15 or 107-16 code is active
Repair: Refer to Troubleshooting, Inlet Air is Restricted.
Result: There are no restrictions in the air inlet or exhaust system.
Proceed to Test Step 7.
Contact with high pressure fuel may cause fluid penetration and burn hazards. High pressure fuel spray may cause a fire hazard. Failure to follow these inspection, maintenance and service instructions may cause personal injury or death.
Contact with high-pressure fuel may cause personal injury or death. Wait 10 minutes after the engine has stopped to allow fuel pressure to purge before any service or repair is performed on the engine fuel lines.
Table 2
Troubleshooting Test Steps Values Results
7. Fuel Supply
A. Check for leaks from the high-pressure fuel lines.
B. Ensure that the vent in the fuel cap is not filled with debris.
C. Ensure that the fuel supply valve (if equipped) is in the full OPEN position.
D. If the temperature is below 0 °C (32 °F), check for solidified fuel (wax).
E. Check the filter/water separator for water in the fuel.
F. Check for fuel supply lines that are restricted.
G. Replace the in-line fuel filter that is installed upstream of the Electric Fuel Lift Pump (EFLP).
H. Replace the fuel filter.
I. Check the diesel fuel for contamination. Refer to Systems Operation, Testing, and Adjusting, "Fuel Quality - Test".
J. Check for air in the fuel system. Refer to Systems Operation, Testing, and Adjusting, "Air in Fuel - Test".
Fuel system
Result: There is a leak from a high-pressure fuel line.
Repair: Replace the high-pressure fuel line. Refer to Disassembly and Assembly, "Fuel injection lines - Remove" and Disassembly and Assembly, "Fuel injection lines - Install".
Result: The vent in the fuel cap is blocked.
Repair: Install a replacement fuel cap.
Result: The fuel contains solidified wax.
Repair: Replace the fuel with fuel of the correct specification for the ambient conditions.
Result: There are fuel supply lines that are restricted.
Repair: Replace any damaged or restricted fuel lines.
Replace the fuel filter. Refer to the Operation and Maintenance Manual for further information.
Result: There is air in the fuel system.
Repair: Prime the fuel system. Refer to Systems Operation, Testing, and Adjusting, "Fuel System - Prime".
Result: The diesel fuel is contaminated.
Repair: Drain the fuel tank and the fuel system.
Replace the fuel filter. Refer to the Operation and Maintenance Manual for further information.
Fill and prime the fuel system with fuel of the correct specification. Refer to Systems Operation, Testing, and Adjusting, "Fuel System - Prime".
Result: The fuel supply is OK.
Proceed to Test Step 8.
8. Clean the Fuel System
A. Following the instructions on the bottle, add Caterpillar Fuel System Cleaner 343-6210 to the fuel tank.
Electronic Unit Injectors
Result: Performance should be restored within 2-3 hours.
Return the unit to service, the fuel system will be cleaned during operation.
Result: Performance is not restored within 2-3 hours.
Proceed to Test Step 9.
9. Low Compression (Cylinder Pressure)
A. Perform a compression test. Refer to Systems Operation, Testing, and Adjusting, "Compression - Test".
Cylinder compression
Result: The results of the compression test are outside the spe