Fuel Flow

Liquid fuel is injected into the inlet manifold by a positive displacement pump. The fuel flow to the pump is measured with a flow gauge, the gauge ball position being read at its center. A calibration table relates this measured flow to the quantity injected into the manifold.

A similar flow meter is used for gas phase fuels. These are not controlled by an injection pump, but are continuously admitted to the inlet manifold. A solenoid valve turns off the gas supply when the engine is not running.

The fuel/air ratio entering the cylinder can be computed from the measured fuel and air flows when the engine is operating in steady state (constant RPM).