M11 Series – Service Manual – 005-010   Fuel Consumption

Refer to the fuel consumption check list sheets in the back of Section TS.

NOTE: The most accurate method to check the fuel consumption is to weigh the fuel used. Use a scale capable of measuring within 0.045 kg [0.1 lb] to weigh the fuel tank. Use a remote mount tank with enough capacity to run 80 km [50 mi].

Fill the fuel tank. Weigh the tank with the fuel. The weight on No. 2 diesel fuel is nominally 0.844 kg per liter [7.03 lb per gallon].

Install the remote tank (1).

Measure the distance traveled with an accurate odometer. The odometer accuracy can be checked by using measured miles or kilometers.

After traveling the route, remove the tanks, and weigh the remaining fuel. Compute the fuel used in liters [gallons] as required.

Compute the kilometers per liter or miles per gallon.

In addition to the measurement of the fuel used, the following factors provide points for running a test similar to the recognized Type II Society of Automotive Engineers Fuel Test.

These procedures are helpful in determining differences in fuel consumption between two vehicles under the same environmental, road, and test conditions.

Perform the test with the test vehicle and a control vehicle. The control vehicle compensates for changes in traffic conditions.

The vehicles

must stay close together to experience the same varying traffic and weather conditions, but

not so close as to affect each other’s driving or headwind.

The test course

must be 65 to 80 km [40 to 50 mi] long.

This test route and truck weights

must not change during the test.

All of the test results are based on comparing the fuel used by the test truck to the fuel used by the control truck.

Drive the truck on a warm-up test run. Drive enough tests to achieve:

• Difference in elapsed time between each test run can

  only be plus or minus 0.5 percent. This will be ±15 seconds on 80 km [50 mi] at 60 mph.

The fuel usage of the test truck between test drives

must
fall within a 2-percent range (6.00 mpg vs. 6.12 mpg).

The same range also applies between drives of the control truck.

NOTE: The differences in traffic and driving practices can make the test drive fall out of the 2-percent range.

A minimum of three test drives that meet these conditions make a valid test. A single test drive is unreliable.

Use the same experienced drivers for all of the tests.

NOTE: The vehicle speeds

must be representative of a typical operation.

During the test, record the following:

• Ambient temperature
• Humidity
• Barometric pressure
• Wind velocity
• Wind direction.

NOTE: Avoid testing under any extreme conditions.