SNIP

    I faced the same challenge when putting a 2nd gen six port 13B in an
RV-6A.  I did not want to have to mess with return fuel lines and

switches.

So I built a small rectangular (1 1/2x3x8 inches) aluminum tank out of
aluminum rectangular tubing by welding plates on both ends and AN-

fittings

for fuel.  The high pressure EFI pumps (two) each have there own feed

line

from the bottom of this tank.  The tanks is located low on the fire

wall and

is fed from two wing tanks by a single selector which switches

between them.

  The two EFI pumps pull fuel from this header tank for the injectors and
returns unused fuel via a pressure regulator to the top of this same

header

tank.  Any fuel actually injected creates a partial vacuum in the header
tank which pulls the fuel from the wing tanks to replace the fuel used.
This partial vacuum is substantial and will pull fuel up at least 24".  I
also have a boost pump in the low pressure portion of the fuel line

to the

header tank for take off and landing insurance.

It has worked fine for me.  The only two possible problems might be

having

the header tank get too hot which could potentially create a vapor lock
(although turning on the boost pump should eliminate this problem

should it

occur and of course placing the tank in some location other than the

engine

compartment) and if you should have a leak in the tank then the partial
vacuum would suck air instead of fuel.  However pressure testing the

welding

should remove that problem.

  I have 75 hours flying with this arrangement which requires no return
lines nor any multi port switches.

Best Regards

Ed Anderson
Matthews NC

Wow Ed!!,...........Talk about simplicity. I think
it's "BRILLIANT", sure beats all that extra
valving/plumbing............Any comments on this guys?

                                       Butch Diaz Sr.

Bill Freeman wrote: 
Many C210s had significant "fuel interruption" incidents when they were using a
system something  like this.  The problem was not having a way to vent fuel
vapor from
the sump tank back to the mains or to the air.  Since the fuel pump supplies
max fuel
flow plus some safety factor, at cruise it is bypassing a LOT of fuel back
to the
tank and heat will build up in the fuel.  In case this is not clear, fuel is
heated when
pumped.  Cessna modified the C210 system with a vent back to the mains and
MUCH larger fuel lines which actually permit fuel vapor bubbles to counterflow
back to the wing tanks without interrupting the liquid fuel flow down to the
sump.

I will say once again.  Please be VERY VERY careful when you are redesigning
your fuel system.  Many very smart engineers have built and CERTIFIED fuel
systems only to find out that there were hidden glitches that only came out
later,
usually resulting in engine failure.   I would suggest in the strongest
possible terms
that everyone please copy a well established fuel system and leave experimenting
to easy stuff like changing the airfoil shape of the wing or redesigning the
EFI.   : - )

Please take no offense, but I really do worry.

Bill

 
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