81148M Mariner THROTTLE ARM ASS'Y

Probable Causes
Codes
Parameters
Throttle Signal
Air Inlet and Exhaust System
Fuel System
Engine Load
Valve LashRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in order.Note: If the problem only occurs under certain conditions, test the engine under those conditions. Examples of certain conditions are high engine speed, full load, and engine operating temperature. Troubleshooting the symptoms under other conditions can give misleading results.
Table 1
Troubleshooting Test Steps Values Results
1. Engine Derate or Active Codes
A. Certain diagnostic codes and/or event codes may cause poor performance. Refer to the histogram information for engine derates in Cat ET. Check for the following histograms:
1. High Exhaust Temperature Prevention Derate Time Histogram
2. High Turbo Speed Prevention Derate Time Histogram
B. If the histograms contain derates and no diagnostic codes are present, then the engine is operating normally. The following list contains conditions that can cause derates:
1. Elevated altitude
2. Elevated inlet air temperature
3. Elevated ambient temperature
Engine Derate or Active Codes Result: A diagnostic code is present.
Troubleshoot the code and then reset the histogram.
Result: A diagnostic code is not present.
Proceed to Test Step 2.
2. Incorrect Parameters
A. Use Cat ET to verify that the correct parameters are being used. Refer to Troubleshooting, "Configuration Parameters" for additional information.
Parameters Result: The parameters are correct.
Proceed to Test Step 3.
Result: The parameters are not correct.
Input the correct parameters. Refer to Troubleshooting, "Configuration Parameters" for additional information.
3. Throttle Signal
A. Monitor the status for "Throttle Position" on Cat ET. Verify that the status for "Throttle Position" is stable and that the engine is able to reach high idle speed.
Throttle Signal Result: The throttle signal is stable.
Proceed to Test Step 4.
Result: The throttle signal is not stable.
Make the necessary repairs, Refer to the appropriate circuit test.
4. Restriction in the Air Inlet and Exhaust System
A. Observe the check engine lamp. Check for an air filter restriction indicator. Replace any plugged air filters. Refer to the Operation and Maintenance Manual.
B. Check the air inlet and exhaust system for restrictions and/or leaks.
Restrictions Result: There are no restrictions in the air inlet or exhaust system.
Proceed to Test Step 5.
Result: There are restrictions in the air inlet or exhaust system.
Make the necessary repairs, Refer to Systems Operation/Testing and Adjusting, "Air Inlet and Exhaust System - Inspect" for additional information.
5. Check the Fuel System
Refer to Systems Operation/Testing and Adjusting, "Fuel System" for additional information.
A. Visually check the fuel level in the fuel tank. Do not rely on the fuel gauge only.
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. Inspect the fuel system. Refer to Systems Operation/Testing and Adjusting, "Fuel System - Inspect" for additional information.
E. 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. Cold mode (if applicable) 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.
Refer to "Cold Mode Operation" within the Systems Operation, "General Information".
F. Check fuel quality. Refer to Systems Operation/Testing and Adjusting, "Fuel Quality - Test" for the proper procedure. Check the fuel tank for debris or foreign objects which may block the fuel supply.
G. Check for the proper operation of the fuel transfer pump. Refer to Systems Operation/Testing and Adjusting, "Fuel System" for test information.
Fuel system Result: The fuel pressure is OK.
Proceed to Test Step 6.
Result: The fuel pressure is not OK.
Replace the fuel filters. Clean the primary filter/water separator of debris. Refer to the Operation and Maintenance Manual for details.
6. Engine Load
A. Check accessories and parasitic loads on the engine.
Engine loads Result: There is not a parasitic load.
Proceed to Test Step 7.
Result: There is a parasitic load.
Remove the parasitic load.
7. Valve Lash
A. Check the valve lash. The valve lash can affect the performance of the engine.
Valve lash Result: The valve lash is not set correctly.
Set the valve lash. Refer to Testing and Adjusting, "Engine Valve Lash - Inspect/Adjust" for the correct procedure.
Complete the procedure in the order in which the steps are listed.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).