Other than physical damage, which should be handled by proper, stress-free mounting, the only failure mode I see is the valve getting stuck on one tank or the other.  This can be handled by tee-ing into all supply and return lines, and connecting them with a ganged mechanical on-off valve.  If the electric valve gets stuck, pull the mechanical ones on to allow fuel to crossover.  Basically, creating a Tee fitting into whichever port is open. 

I'm actually working on this for a Corvair installation, but this forum is the only one I've found where an idea can be discussed on its merits, instead of its compliance with standard practice.

On Tuesday, October 28, 2014 10:33 AM, Mitchell Williams <flyrotary@lancaironline.net> wrote:

http://products.pollakaftermarket.com/Asset/42-159%20IS_41-revdd.pdf

On Mon, Oct 27, 2014 at 6:19 PM, Stephen Izett <flyrotary@lancaironline.net> wrote:

I stand corrected. I believe Charlie is correct.

Steve Izett

On 28 Oct 2014, at 6:47 am, Charlie England <flyrotary@lancaironline.net> wrote:

On 10/27/2014 4:55 PM, Ernest Christley wrote:

This is the type that I'm referring to:

http://products.pollakaftermarket.com/item/fuel-selector-valves/light-truck-6-port-motor-driven-valve/42-302

On Monday, October 27, 2014 5:50 PM, Ernest Christley <flyrotary@lancaironline.net> wrote:

Is anyone familiar with electric fuel selector valves as used in automotive applications.  I'm trying to figure out how they operate.  Do they select one line when power is applied to a solenoid type plunger, and then the other line is selected when power isn't applied?  Or does a pulse of power switch them back and forth?  If they maintain the currently selected tank when power is absent, it seems to me that this could remove fuel lines and a leak prone selector valve from a lot of cockpits.  Furthermore, the 6 port models look like they could be plumbed easily to handle return lines.

The ones I've seen actually use a motor to move the valve (think screw jack), so they will remain in last position. Reading your linked item indicates that it works the same way.

'Traditional' engine guys have avoided them in the past because they're plastic and they require power (and they are an automotive product, so they can't be reliable ;-)  ). They are probably worth considering, but I'm seriously looking at switching to in-tank turbine pumps with automotive style PWM control; no return line needed. Then tank selection would be with a switch on the panel instead of a valve. Downside is that for total redundancy, I'd need 2 pumps in each tank. They are dirt cheap (<$20 each), but controllers are around $75 ea and switching gets pretty elaborate if there are more than 2 tanks.

Charlie

--
Mitchell Williams OKPE, ATP/CFI/A&P/IA   www.chickashawings.com
of shadow and ash http://www.amazon.com/dp/B009KZGVQS