Originally Posted by rvbuilder2002
Do some reading on the way mechanical fuel injection works.
The throttle arm on the servo / throttle body opens and closes the throttle plate (butterfly) and controls a fuel pressure regulator within the servo that varies the fuel pressure in the fuel line that links to the distribution manifold on the top of the engine.
This variable fuel pressure is what regulates the amount of fuel that flows out of the constant flow injectors.
I did do some reading Scott, and what I read is pretty specific that AIRFLOW through the servo determines how much fuel is released to the flow divider. If the engine is not running, there is no airflow through the servo. It doesn't matter what position the throttle plate is in.
My RV-10 has an AFP fuel system, which Don says is the same basic system as Bendix.
From the AFP manual: "The FM-series fuel injection system uses the proven principal of mass airflow metering to proportion the fuel flow to the engine.
The FM-series system is a mass airflow device employing a venturi to generate a signal corresponding to the mass airflow..."
So if there is no airflow (as when priming a non-running engine), what difference does it make if the throttle plate is open or closed?