John Slade wrote:

Builders,
Before I dive in and drill holes, I wonder if I could get some

opinions on

my plan for an EFI fuel system on my Cozy. It's modeled after that

used by

Tracy Crook in his RV. I have installed the plans fuel valve and

have the

gascolator ready. The much discussed EFI return problem now rears

it's ugly

head. After sorting through all the opinions I'm ready to go with

a transfer

pump system as shown at http://kgarden.com/cozy/fuel.jpg

The idea is to run a transfer pipe from the right to the left

tank. The pipe

would come out of the rear of the right tank about 12 inches

outboard of the

fuselage side and just above the inside base of the spar, through

the spar

to the firewall. It would then go via a Facet low pressure pump on

the

firewall to a similar line entering the top of the left tank. The

EFI return

line would go to the top of the left tank through the spar.

Since my strakes are now sealed, I'm hoping I'll be able to get at

the three

new fuel lines from the filler cap to apply flox and get a good

seal. I'll

also be able to reach into the spar hollow to seal the lines as

they enter.

All input, including neat ideas for sealing the pipes as they

enter the

tank, would be appreciated.

I understand that the main disadvantage of this system is pilot

workload.

Builder's who haven't sealed their strakes - solve this issue

before you do!

John (its soooo much easier if you stick to the plans) Slade
Cozy MKIV #757, progress: http://kgarden.com/cozy
West Palm Beach, FL

charles.harbert wrote:

John, I would highly recommend that you not do it the way you're suggesting with
a transfer pump. The problem is that the elec fuel pump is constant volume
(about 40 gph), so when the engine is running  you end up with a lot of fuel
being returned to one tank. If it's the tank your drawing from-no problem, but
if its to the other tank, you're rapidly emptying one and filling the other.
Your 15 gph Facet  may not keep up. When your flying with a low amt of fuel left
in the tanks, I believe this could be a formula for disaster.

We've talked about this before, and there seemed to be 2 good alternatives. The
first was to locate a dual line AC fuel selector which I understand are
available. It returns the fuel to the tank that is being used. You'll have to
run a couple more lines up to your selector valve, but you'll get rid of a pump
(and elec load), plus it's fool proof.

Cozy's don't come with a sump tank, but I believe you could install a small one
(in the cabin) after the selector, so that you could return the fuel to this
sump. I don't think you'd need more than a couple gallons to ensure cool fuel.
That's how it's done on my Velocity and it works fine.  You don't need to vent
it because your returning less fuel than you're sending to the engine. Also, you
don't need to add additional fuel lines into your wing tanks.

It's pretty easy to install additional fuel lines into your wing tanks. Just cut
a hole large enough to get the foam out between the 2 glass sides(nickel size).
Fill it with stiff (use some fumed silica) microglass or flox to seal the hole.
Then drill it to accept the fuel line (assume 3/8"). I used aluminum tubing, but
be sure to sand it. I installed it using microglas and put one layer of bid over
it to secure it to the wall. It may not be as pretty as the line you originall
put in, but it will be strong. Also, blue foam is suppose to resist fuel
degradation-that's why we use it around the fuel tanks.

I think you are wrong about the blue foam Chuck. Easy to check.

Paul Lamar

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