Symptom Tree t087
Cause | Correction |
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Interview the operator to verify the complaint |
Refer to Fuel Consumption General Information and Customer Complaint Form at the end of Section TS. Follow the instructions on the form before continuing with this tree. |
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Operator technique is not correct |
Explain correct engine operation to the operator. Refer to Section 1 of the Operation and Maintenance Manual ISM and ISMe Engines, Bulletin 3666319. |
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VE/VMS® analysis uses incorrect data |
Review the VE/VMS® data and compare to the vehicle and engine specifications. Do not use more than 20 percent for the Aero value. Refer to the VE/VMS User’s Manual. |
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Equipment and environmental factors are affecting fuel consumption |
Consider ambient temperatures, wind, tire size, axle alignment, routes, and use of aerodynamic aids when evaluating fuel consumption. |
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Drivetrain is not correctly matched to the engine |
Check for correct gearing and drivetrain components. Refer to the OEM vehicle specifications. |
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Electronic fault codes active or high counts of inactive fault codes |
Read the fault codes with an electronic service tool. Refer to Section TF in the Troubleshooting and Repair Manual Electronic Control System ISM and QSM11 Engines, Bulletin 3666266 and the Troubleshooting and Repair Manual CM870 Electronic Control System ISM Engines, Bulletin 4021381. |
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Programmable parameters or selected features are not correct |
Check the programmable parameters and the selected features with an electronic service tool. Set the parameters and features again if necessary. Refer to the appropriate electronic service tool manual. |
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Turbocharger is not correct |
Check the turbocharger part number and compare it to the Control Parts List (CPL), Bulletin number 3379133 or 4021327. Replace the turbocharger if necessary. Refer to Procedure 010-033. |
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Fuel leak |
Check the fuel lines, fuel connections, and fuel filters for leaks. Check the fuel lines to the supply tanks. Refer to Procedure 006-024 and the OEM service manuals. |
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Hubometer or odometer is miscalibrated |
Check the hubometer and odometer calibrations. Calibrate or replace the hubometer or odometer, if necessary. Calculate fuel consumption with new mileage figures. |
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Fuel grade is not correct for the application or the fuel quality is poor |
Operate the engine from a tank of high-quality fuel. Refer to Fuels for Cummins Engines, Bulletin 3379001. |
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Lubricating oil level is above specification |
Check the oil level. Verify the dipstick calibration and oil pan capacity. Fill the system to the specified level. Refer to Procedure 007-009 or 007-025. |
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Electronic control module (ECM) calibration is malfunctioning |
Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history for applicable fixes to the calibration stored in the ECM. Refer to the calibration history spreadsheet Click here to see ecm_calibration_rev_history.xls on QuickServe® Online Internet Website or the INCAL™ calibration CD. Compare the calibration stored in the ECM with the engine rating and the Control Parts List (CPL), Bulletin 4021326 or 4021327. If necessary, recalibrate the ECM. Refer to Procedure 019-032 in the Troubleshooting and Repair Manual Electronic Control System ISM and QSM11 Engines, Bulletin 3666266 and the Troubleshooting and Repair Manual CM870 Electronic Control System ISM Engines Bulletin 4021381. |
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Vehicle speed sensor (VSS) is not correct |
Use an electronic service tool to monitor the vehicle speed while the vehicle is not moving. Refer to the appropriate electronic service tool manual. If necessary, install the correct VSS. Refer to in the Troubleshooting and Repair Manual Electronic Control System ISM and QSM11 Engines Bulletin 3666266 and the Troubleshooting and Repair Manual CM870 Electronic Control System ISM Engines, Bulletin 4021381. |
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Air intake system restriction is above specification |
Check the air intake system for restriction. Clean or replace the air filter and inlet piping as necessary. Refer to Procedure 010-031. |
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Intake manifold pressure (boost) is below specification |
Refer to the Intake Manifold Pressure (Boost) is Below Normal symptom tree. |
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Air intake or exhaust leaks |
Inspect the air intake and exhaust systems for air leaks. Refer to Procedure 010-024. |
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Charge air cooler is restricted or leaking |
Inspect the charge air cooler for air restrictions or leaks. Refer to Procedure 010-027. |
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Exhaust system restriction is above specification |
Check the exhaust system for restrictions. Refer to Procedure 011-009. |
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Injector is malfunctioning |
Perform the single-cylinder cutout test. Replace the injectors as necessary. Refer to Procedure 006-026 or 014-002. |
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Overhead adjustments are not correct |
Measure and adjust the overhead settings. Refer to Procedure 003-004. |
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Fuel consumption has increased after an engine repair |
Evaluate the engine repair to determine its effect on fuel consumption. Check part numbers to make sure the correct parts were used. Refer to the Control Parts List (CPL), Bulletin 3379133. |
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Internal engine damage |
Analyze the oil and inspect the filters to locate an area of probable damage. Refer to Procedure 007-002. |
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Vehicle speed sensor (VSS) or circuit is malfunctioning |
Check the vehicle speed sensor and circuit. Refer to Procedures 019-090 and 019-091 in the Troubleshooting and Repair Manual Electronic Control System ISM and QSM11 Engines, Bulletin 3666266, or the Troubleshooting and Repair Manual CM 870 Electronic Control System ISM Engines, Bulletin 4021381. |