Two methods can be used to determine the flow rate of fuel consumed.

The first method employs a precision lab scale and a stopwatch: Simply divide the change in mass of the red fuel tank by the amount of time.

The second method uses two turbine flow meters: One to measure the flow rate of fuel to the engine; the other measures the flow rate coming from the engine back to the fuel tank. The difference is the flow rate of fuel consumed. This method is less accurate at low consumption rates. You can see the two flow meters that are T-ed in-line. The sheet metal box covers the fuel pump to make it quieter.