M11 Series Engines – Fuel Consumption Excessive (CELECT™ or CELECT™ Plus)

Symptom Tree  t087-155

This is symptom tree t087-155
Cause Correction

For heavy-duty automotive applications, continue with this tree or refer to Troubleshooting Excessive Fuel Consumption Complaints, Bulletin 3666094.

If the Fuel Consumption Complaint also includes a driveability or low power complaint, refer to the Driveability/Low Power Customer Complaint Form at the end of Section TS.

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.

 

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 Fuel Consumption – General Information and Customer Complaint Form at the end of Section TS.

 

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.

 

Oil and fuel consumption calculations are not correct

Verify the fuel consumption calculations. Verify the calibration plug (Heavy Duty). Verify Centinel™ control module calibration values (High Horse Power). Refer to Fuel Consumption – General Information and Customer Complaint Form at the end of Section TS.

 

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.

 

Electronic fault codes active or high counts of inactive fault codes

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

 

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.

 

Coolant temperature is below specification

Refer to Coolant Temperature Below Normal symptom tree.

 

Lubricating oil temperature is below specificationCoolant 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 OEM service manual.

 

Wheel alignment is not correct (tractor or trailer)

Check the wheel alignment. Refer to 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.

 

Oil and fuel consumption calculations are not correct

Verify the fuel consumption calculations. Verify the calibration plug (Heavy Duty). Verify Centinel™ control module calibration values (High Horse Power). Refer to Control Parts List (CPL), Bulletin 3379133.

 

Operator technique is not correct

Explain the correct engine operation to the operator. Refer to Operation and Maintenance Manual, M11 Series Engines for Transit, Bulletin 3666072, or the Operation and Maintenance Manual, Bulletin 3666117.

 

Fuel leak

Check the fuel lines, fuel connections, and fuel filters for leaks. Refer to 006-024 and OEM service manuals.

 

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, CELECT™ Plus Fuel System, Bulletin 3666130, or in the Troubleshooting and Repair Manual, CELECT™ Fuel System, 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 007-009 and 007-025.

 

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 appropriate electronic service tool manual.

 

Electronic control module (ECM) is not correct

Check the ECM part number and compare it to the Control Parts List, Bulletin number 3379133 or 4021327. Replace the ECM if necessary. Refer to Procedure 019-032 in the Troubleshooting and Repair Manual, CELECT™ Plus Fuel System, Bulletin 3666130, or in the Troubleshooting and Repair Manual, CELECT™ Fuel System, Bulletin 3666084, and the appropriate electronic service tool manual, .

 

Air intake system restriction

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

 

Exhaust system restriction

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

 

Intake manifold pressure (boost) is below specification

Refer to 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 010-024.

 

Charge air cooler is restricted or leaking

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

 
Last Modified:  28-Mar-2005