N14 Base Engine Troubleshooting and Repair Manual – Fuel Consumption Excessive (CELECT™ or CELECT™ Plus)

Interview the operator to verify the complaint

Refer to the Fuel Consumption – General Information and Customer Complaint Form at the end of Section TS. Follow the instructions on the forms before continuing with this tree.

Fuel economy expectations are not reasonable

Verify what factors compose the operator’s expectations. Run a VE/VMS® simulation for automotive applications to determine the expected fuel economy or perform a trial run to establish the actual fuel economy. Refer to the OEM specfications.

Fuel consumption is changing due to seasonal or operational changes

Review fuel consumption records for the past 3 to 6 months to determine the effects of seasonal or operational changes.

Drivetrain is not correctly matched to the engine

Check for correct gearing and drivetrain components. Make sure the propeller size is correct.

Vehicle has changed routes or loads

Consider operating environment and its effect on fuel economy. Adverse weather, strong head winds, variable routes, and heavier loads can increase fuel consumption.

Fuel grade has changed

Number 1 diesel fuel and other light winter fuels are lower in heat content than number 2 diesel fuel and result in higher fuel consumption. Evaluate fuel consumption using number 2 diesel fuel. Fuel additives also result in lower heat content.

Electronic fault codes active or high counts of inactive fault codes

Refer to Section TF in the Troubleshooting and Repair Manual for CELECT™ Plus Systems, Bulletin 3666130, or Section TF in the Troubleshooting and Repair Manual for CELECT™ Systems, Bulletin 3666084.

Coolant temperature is below specification

Refer to the Coolant Temperature Below Normal symptom tree.

Lubricating oil temperature is below specificationthe Coolant Temperature Below Normal symptom tree

Install an oil pan heater, or drain the oil and fill the system with warm oil.

Vehicle or trailer brakes are dragging

Check the brakes for dragging. Refer to the OEM service manual.

Wheel alignment is not correct (tractor or trailer)

Check the wheel alignment. Refer to the OEM service manual and the manufacturer’s instructions.

Tires on the tractor or trailer are new

New tires add up to 3 percent to rolling radius. Verify tire revolutions per mile with new tires and calculate fuel consumption. For electronic engines, enter the correct value for tire revolutions per mile in the ECM.

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.

Tires on the tractor or trailer are worn or have low-pressure

Check the tires on the tractor and trailer. Repair or inflate the tires as necessary. Evaluate fuel consumption again.

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.

Operator technique is not correct

Explain correct engine operation to the operator. Refer to the OEM service manual.

Fuel leak

Check the fuel lines, fuel connections, and fuel filters for leaks using the combustible gas detector service tool. Refer to Procedure 006-024.

Vehicle speed sensor (VSS) tampering has occurred

Check the vehicle speed sensor and circuit for tampering. Check for Fault Code 242. Repair the circuit as necessary. Refer to Procedures 019-090 and 019-091 in the Troubleshooting and Repair Manual for CELECT™ Plus Systems, Bulletin 3666130, or in the Troubleshooting and Repair Manual for CELECT™ Systems, Bulletin 3666084.

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 Procedures 007-009 and 007-037.

Programmable parameters or selected features are not correct or are not set the same as the values in comparable vehicles

Check the programmable parameters and the selected features with an electronic service tool. Make sure that gear-down protection road speeds are set to the same values as in comparable vehicles. Refer to the appropriate electronic service tool manual and Procedure 019-078 in the Troubleshooting and Repair Manual for CELECT™ Plus Systems, Bulletin 3666130, or the Troubleshooting and Repair Manual for CELECT™ Systems, Bulletin 3666084.

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 for CELECT™ Plus Systems, Bulletin 3666130, or the Troubleshooting and Repair Manual for CELECT™ Systems, Bulletin 3666084.

Air intake system restriction

Check the air intake system for restriction. Refer to Procedure 010-031.

Exhaust system restriction

Check the exhaust system for any restrictions. Refer to Procedure 011-009.

Intake manifold pressure (boost) is below specification

Refer to the Intake Manifold Pressure (Boost) is Below Normal symptom tree.

Air intake or exhaust leaks

Inspect the air intake and exhaust systems for air leaks. Refer to Procedure 010-024.

Charge air cooler is restricted or leaking

Inspect the charge air cooler for air restrictions or leaks. Refer to Procedure 010-027.