<VV> Mechanical Fuel Pump reverse flow?

[Daniel Monasterio]

    The mechanical pump has two check valves to allow fuel moving in one
direction only while the diaphragm pulsates so, if you connect both outlets,
the fuel from the electric pump will not pass (reverse flow) thru the
mechanical pump, assuming the check valves are in good condition. Pulsating
electric pumps have check valves, too but don't know if rotary ones allow
reverse flow or not.
    I remember having seen something about fuel pumps in airplanes at
http://flycorvair.com/ , think you could get good ideas in this website.

    Daniel Monasterio

<<On my airplane's Corvair engine, I am planning to use the mechanical fuel
pump but also have an electric fuel pump in parallel that I can switch in,
in case of vapor lock or failure of the mechanical pump.  Does anybody know
whether the mechanical pump has a mechanism that would act as a check
valve, preventing the reverse flow of fuel backward through the pump when I
switch the electric one on?>>