Hi Paul,

In my glass goose, I plan to have both upper wing tanks draining into
a common header tank under the engine.  The header tank will contain
twin submersible Walbro pumps, with appropriate check valves,
filters, etc., leading to the fuel rail.  Due to space limitations,
this tank can only hold about 3 gallons.

I can route the return fuel directly back into this tank or to the
inboard fuel sending towers in each wing tank. With the latter, I
don't have a good way to assure equal return flow to both wing tanks,
and the rapid flow might disturb the fuel level sensors.

My question is whether the fuel in a 3-gal tank might get too hot
after being continually cycled through the engine?  If that is
likely, I could probably squeeze in a small fuel cooling radiator
prior to returning to the header tank.

Thanks,

Scott Gettings

That is a good question Scott. At high power the return flow is
    less. The thing to do is install some way to measure the temperature
    in there and let the engine idle. That will be a worse case scenario.

    By sending the fuel back to only one of the main tanks you risk a fuel
    transfer problem. Airplanes have crashed because of this. They selected
    one tank and it ran out of gas much faster than expected.

    Paul Lamar


    Could you pair a couple of fuel selector valves so that the return is then
sent to the tank being used for supply. It would need to be ganged to
ensure switching at the same time.

   Dale Davies

Most EFI systems send unneeded fuel back to the fuel tank.
We had many many discussions about this. EFI is very rare in aircraft
engines and aircraft typically have more than one fuel  tank so it became
a real serious problem. We had at least one fatality when the fuel selector
switch moved and the engine failed on take off.

Statistically high wing airplanes with a "booth" selector switch are safer
than low wing airplanes. Low wing airplanes will lose pressure when
a switch is on both and one tank is empty so a booth position
is not used with the pump or pumps out side the fuel tank or tanks.

Also one must be careful not to use tank vents that face forward into
the airstream as dynamic pressure alone can transfer fuel from one
thank to another.

Here are some collected  3D's.

Paul Lamar

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