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Not to debate the subject, but the return line teed back to the fuel line
between the selector valve and the aux pump is a short simple run. The
mechanical/aux pumps give redundancy. That is how factory, low wing, fuel
injected planes work.

>I was looking at the schematics for Simon Creasy's aircraft and liked the
>KISS system which he incorporated to keep the header tank full... provide
>a float switch which controls the power to both transfer pumps at once.
>If one transfer pump moves more fuel than the other requiring some
>intervention, switch from AUTO to MANUAL mode to pump from the fuller tank.
>A valved crossover would eliminate the failure mode of one transfer pump
>giving up the ghost.

That doesn't sound simple at all, in fact it sounds quite complex, both
to build and manage.

Bill

[Hi Bill, thanks for the heads up on that return line... that makes lots
of sense to me.  Keep it under the cowl and eliminate having to worry about
plumbing it back behind the firewall at all.  I hardly think your comments
could be considered debating the subject, as the reason I posted the
question in the first place was to learn about the different ways that
folks had setup their fuel systems... I really appreciate the input.

I overcomplicated Simon's system a bit, he was kind enough to write me
and point out the error of my ways.  If there is an unbalanced
situation he simply turns off the CB switch for the transfer pump from
the lighter wing and leaves the system in AUTO.  The MANUAL position is
provided strictly as a backup for a failure of the relay which is pulled
up by the float switch.  The part about the valved crossover was mine, it
is not a part of his present system.   <Marv>   ]