WingedFrog
Well Known Member
Has anyone a figure for the fuel pressure we can expect from the mechanical fuel pump? I have got the new model made in Italy and after installing a switch on the electric fuel pump of my RV-12, I am getting in flight pressure of 1 to 2 psi with the electric fuel pump off. With both pumps on I get a hefty 4.8 to 5, close to the yellow high and with engine off the electric pump gives about 3.7 psi which is consistent with the reading with both pumps on. As I feel uncomfortable with the low reading of the mechanical pump I leave the electrical pump on in flight. The practice in the SportCruiser which is certified equipped with a fuel pump switch is to have the electric fuel pump on only for take-off and landing. I had the feeling that this practice would allow to better detect a potential failure of the mechanical pump through the low pressure alarm but operating with such a low fuel pressure, at the edge of the yellow low may be questionable.
