Cummins ISX11.9 CM2250 – Service Manual Fuel Consumption Excessive

Interview the operator to verify the complaint

Refer to the Fuel Consumption General Information and Customer Complaint Form in Procedure t00-004 in Section TS. Follow the instructions on the form before continuing with this tree.

Operator technique is not correct

Explain correct engine operation to the operator. Refer to Procedure 101-015 in Section 1 of the Operation and Maintenance Manual, ISX11.9 CM2250, Bulletin 2883444.

VE/VMS® analysis uses incorrect data

Review the VE/VMS® data and compare it 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.

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.

Drivetrain is not correctly matched to the engine

Check for correct gearing and drivetrain components. Refer to the OEM service manual.

Electronic fault codes active or high counts of inactive fault codes

Refer to Section TF of the Fault Code Troubleshooting Manual, Bulletin 4022225.

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 Procedure 019-078 in Section 19
.

Turbocharger is not correct

Check the turbocharger part number and compare it to the Control Parts List (CPL), Bulletin 4021328. Replace the turbocharger if necessary. Refer to Procedure 010-033 in Section 10
.

Fuel leak

Check the fuel lines, fuel connections, and fuel filters for leaks. Check the fuel lines to the supply tanks. Refer to the OEM service manual.

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.

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 Procedure 018-002 in Section V of the Operation and Maintenance Manual, ISX11.9 CM2250, Bulletin 2883444.

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 and
Procedure 007-037 in Section 7.

Electronic control module (ECM) calibration is malfunctioning

Verify that 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 4021328. If necessary, calibrate the ECM. Refer to Procedure 019-032 in Section 19
.

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
Procedure 019-091 in Section 19
.

Vehicle speed sensor (VSS) or circuit is malfunctioning

Check the vehicle speed sensor and circuit. Refer to Procedure 019-091 and
Procedure 019-093 in Section 19.

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 Procedure 019-091 and
Procedure 019-093 in Section 19.

Air intake system restriction is above specification

Check the air intake system for restrictions. Clean or replace the air filter and inlet piping as necessary. Refer to
Procedure 010-031 in Section 10
.

Exhaust system restriction is not within specification

Check the exhaust system for restrictions. Refer to
Procedure 011-009 in Section 11 .

Injector(s) are malfunctioning

Perform diagnostics to find the damaged injector(s). Replace the injector(s) as necessary. Refer to Procedure 006-026 in Section 6 or
Procedure 014-008 in Section 14.

Turbocharger is malfunctioning

Monitor the turbocharger boost pressure with an electronic service tool. Refer to the Engine Performance Troubleshooting symptom tree in Section TT. Check the turbocharger variable geometry operation (if applicable).

Overhead adjustments are not correct

Measure and adjust the overhead settings. Refer to
Procedure 003-004 in Section 3
.

Internal engine damage

Analyze the oil and inspect the filters to locate an area of probable damage. Refer to
Procedure 007-083 in Section 7
.