I have a question for people with electronic fuel injection systems.  My
    question involves the tank setup and return lines.   On a Cozy with a 20b.
    I have a sump tank and I planned on having check valves between the wing
    tanks and the back seat sump tank. ( I am using Infinity retracts )  I'm
    not
    using a tank selector valve.  Only a fuel system on/off valve.   I want it
    simple yet right.  I have 1/2" stainless tubing between the tanks and
    1/2"
    outlet from the sump.  Now I'm concerned about the return line from the
    Fuel
    Injection.  Will the pressure of the heated return lines keep the check
    valves from allowing more fuel into the sump?  I plan on a vented system in
    all tanks but then worry that any pressure could push fuel out of the sump
    vent line.  I planned on having positive air pressure on the vent lines
    during flight by facing the outlets into the wind or "jetstream"

    I've got notes from other past questions on this group that suggest the
    check valves but I'm not sure they are using EFI and I wonder where they
    are
    returning the fuel.

    Rick Irwin



My opinion  is that the deciding factor would be the pressure from the
ram-air vents. The fuel injection system will be returning less fuel
than it takes from the sump tank. The overall pressure will be whatever
the ram air supplies to the tanks. If the pressure to all the tanks is
the same, in theory you should have no problem. -In theory.


I copied Tracy Crook's setup- all fuel to the engine taken from and
returned to  the right tank, and a facet pump transfers fuel from the
left to the right pump. I elected to heed the age-old advise- keep it
simple.



That's my opinion, but I am a product of public education, so follow it
at your peril.



Brian Trubee

Be very very very careful about using dynamic pressure vents. Vents facing forward.
At speed, dynamic pressure alone can empty a tank in minutes. Use something
that is proven to work. Follow the Cozy plans exactly.  I would be wary of
using one way valves.

There are dozens of pit falls to fuel systems. Improperly
designed fuel systems are a leading cause of crashes.

If you use an Andair valve make sure it is in a place that
cannot inadvertently be switched by objects in the cockpit
such as knees and elbows.