0434139 JOHNSON CARBURETOR ASSEMBLY

Probable Causes
Software
Inlet air restriction
Sensor
Fuel quality
Valve lash
Gear trainRecommended Actions
Table 1
Troubleshooting Test Steps Values Results
1. Ensure that the latest Flash File Software is Installed in the All the ECMs
Note: The ECMs need to have the latest software and not mismatched releases.
A. Connect Cat® Electronic Technician (ET) to the service tool connector.
B. Use Cat ET to verify that the correct flash file is being used.
Flash File
Result: The latest flash file is installed.
Proceed to Test Step 2.
Result: The latest flash file is not installed.
Repair: Perform the following procedure:
1. Download the latest flash file from SIS web.
2. Install the software into the ECM.
Refer to Troubleshooting, "ECM Software - Install", for additional information.
If the problem is not resolved, proceed to Test Step 2.
2. Check for a Restriction in the Inlet Air System
A. Check the air filter restriction indicator, if equipped. Refer to the Operation and Maintenance Manual.
B. Measure the inlet air restriction for each turbocharger. Refer to Troubleshooting, "Inlet Air Is Restricted" for additional information.
Restriction
Result: The inlet air restriction is OK.
Proceed to Test Step 3.
Result: The inlet air restriction is NOT OK. An imbalance in the system is discovered.
Repair: Repair or replace damaged inlet air system components. Equalize the inlet air restriction for each of the turbochargers.
If the problem is not resolved, proceed to Test Step 3.
3. Check for Proper Operation of the Intake Manifold Pressure Sensor
A. Connect Cat ET.
B. Use Cat ET to monitor following pressure:
- "Intake Manifold Pressure"
C. Ensure that the reading is steady and varies with engine speed and load.
D. Verify that the status of the "Intake Manifold Pressure" is 0 kPa (0 psi) while the engine is not running.
Sensor
Result: The intake manifold pressure sensor appears to be operating correctly.
Proceed to Test Step 4.
Result: There appears to be a problem with the intake manifold pressure sensor.
Repair: Replace the intake manifold pressure sensor.
If the problem is not resolved, proceed to Test Step 4.
4. Check the Fuel Quality
A. Obtain a fuel analysis. The grade of the fuel affects the rate of fuel consumption. Refer to the engines Operation and Maintenance Manual for additional information.
B. Ensure that the fuel quality is not being affected by cold-weather conditions.
Fuel Quality
Result: The fuel quality is OK.
Proceed to Test Step 5.
Result: The fuel quality is NOT OK.
Repair: Replace the fuel.
If the problem is not resolved, proceed to Test Step 5.
5. Check the Valve Lash
Note: The valve lash can affect the performance of the engine.
Valve Lash
Result: The valve lash is OK.
Proceed to Test Step 6.
Result: The valve lash is NOT OK.
Repair: Reset the valve lash. Refer to Testing and Adjusting, "Valve Lash - Adjust" for additional information.
If the problem is not resolved, proceed to Test Step 6.
6. Inspect the Gear Train
A. Check the following gear train for damage:
- Crankshaft gear
- Camshaft drive gear
B. Verify that the crankshaft and the camshaft drive gears are set with the proper orientation for engine timing.
Gear Train
Result: The gear train has excessive wear.
Repair: Repair or replace damaged gear train components. Refer to the Disassembly and Assembly manual and the Reuse and Salvage Guidelines manual for additional information.
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).