Fuel Consumption Is Excessive
- Active or logged diagnostic codes
- Engine oil level
- Excessive idle or high load
- Fuel System
- Fuel Injectors
- Air inlet and exhaust restriction
Note: The procedures have been listed in order of probability. Complete the procedures in order.
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| Troubleshooting Test Steps | Values | Results |
|---|---|---|
1. Check for Active or Logged Diagnostic Codes A. Check for logged diagnostic codes or active diagnostic codes. If a diagnostic code is logged or active refer to Troubleshooting, Diagnostic Trouble Codes, for more information. |
Codes |
Result: There are logged or active diagnostic codes. Troubleshoot any logged or active diagnostic codes before continuing with this procedure. Refer to Troubleshooting, Diagnostic Trouble Codes for more information. Result: There are no logged or active diagnostic codes. Proceed to Test Step 2. |
2. Check the Engine Oil Level and Obtain an Oil Sample A. Check oil level and obtain an oil sample. If the oil level is high, then take an oil sample to check for fuel dilution. Refer to Troubleshooting, Oil Contains Fuel if fuel is present. |
Oil |
Result: The engine oil sample shows moitor or action required, then skip to Step 5. Make necessary repairs. Result: The engine oil sample and oil level are OK. Proceed to Test Step 3. Result: The engine oil level is not at the correct level. Determine root cause of why the oil level was high or low. |
3. Excessive Idle or High Load A. Use Cat Electronic Technician (ET) to check the Current Totals for excessive idle time and/or for a high load factor. These factors would be indicative of poor operating habits. |
Idle time or load |
Result:The idle times or load was excessive. Reduce idle times or load. Result:The idle times or load was not excessive. Proceed to Test Step 4. |
4. 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. Inspect the fuel system for external leaks. D. Check that there is no air in the clear primary fuel filter. Refer to Systems Operation/Testing and Adjusting, Low Fuel Pressure System- Test. E. Change the primary fuel filter and the in-line filter for the fuel transfer pump. 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. Replace the pre-filter if excessive contamination or if the maintenance interval is exceeded. Refer to Systems Operation/Testing and Adjusting, Low Fuel Pressure System-Test, for test information. |
Fuel system |
Result:The fuel system is OK. Proceed to Test Step 5. Result:The fuel system is not OK. Make necessary repairs. |
5. Fuel Injectors A. If service has been performed on the engine fuel system recently, verify that the injector trim codes in the Engine ECM match the injector for each cylinder. If injectors were moved between cylinders or if an injector was replaced and the injector trim codes were not updated in the Engine ECM, this can cause an engine miss. B. Access the "Cylinder Cutout Test" in the "Diagnostic Tests" under the "Diagnostics" menu. Cut out each cylinder one at a time to listen for improvements in the engine. If engine sound improves while cutting out a specific cylinder or cylinders, then check that the injector(s) are working properly by using 440-6907 Injector Kit. Note: The injector deliver quantity is not a reliable indicator of a failed injector. It is not recommended to use that test in determining if an injector is failed. |
Fuel injectors |
Result: If injector(s) trim codes for each cylinder do not match what is in the Engine ECM, then refer to Special Instruction, REHS9707 for the procedure to install the new injector QR codes within the Engine ECM and on-line. Confirm that this resolves the issue. Result: If injector(s) are found to be defective, then replace the injector(s). Refer to Disassembly and Assembly, Electronic Unit Injector - Remove and Install,. Refer to Special Instruction, REHS9707 for the procedure to install the new injector QR codes within the Engine ECM and on-line. Confirm that this resolves the issue. Note: If two or more injectors are not working properly, this is likely a result of water in the fuel, bad fuel, or contaminated fuel. Contaminated fuel can occur by pre-filling the fuel filter or contamination during a previous repair of the fuel system. The root cause needsto be determinedto prevent a repeat occurrence. Result: There is no previous known service on fuel system and there was no noticeable improvement during the cylinder cut out test. The customer could have ordered injectors through parts and did not change the injector trim codes in the Engine ECM. Visually confirm that the injector trim code for each cylinder matches what is in the Engine ECM. Refer to Special Instruction, REHS9707 for the procedure to install the new injector QR codes within the Engine ECM and online. Proceed to Test Step 6. |
6. Restriction in the Air Inlet and Exhaust A. Inspect the air filter for a restriction. B. Check the air inlet and exhaust system for restrictions and/or for leaks. |
Restrictions |
Result: There are restrictions in the air inlet or exhaust system. Remove or repair the restrictions. |
Complete the procedure in the order in which the steps are listed.
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