REFLECTOR: Franklin
Laurence Coen
lwcoen at hotmail.com
Sat Sep 16 11:49:47 CDT 2006
Hiroo,
Our fuel systems are basically the same with a few minor differences. First
thing that you mention is that your fuel delivery line comes from the bottom
of the sump. The bottom of the sump on my plane goes to the sump drain and
the fuel delivery is located an inch or so higher so that any water or
debris stay in the sump to be drained during preflight. The second thing I
find as odd is that you get flow when you turn on your boost pump. On my
system the head pressure alone will fill my carburetor float bowl. I cannot
open my fuel system anywhere without closing the shutoff valve first. The
opening pressure of the bypass valve could overcome the head pressure and
prevent gravity feed to the carburetor but this shouldn't be a problem if
you run the boost pump until pressure at the carburetor is stable and the
flow is zero. When I turn on my boost pump I don't see any flow and the
pressure comes up in a second or less. The boost pump supplies the pressure
to prime the engine and is then turned off prior to start. Any air in the
fuel line will be purged by running the boost pump. I hope that this is of
some help.
Larry Coen
N136LC
----- Original Message -----
From: Hiroo Umeno
To: Velocity Aircraft Owners and Builders list
Sent: Friday, September 15, 2006 8:46 PM
Subject: Re: REFLECTOR: Franklin
Last weekend, I went to the hangar with my wife. We pulled the cowl off,
pulled the plug and went to work on them. While there was no sign of
deposit evident on them, some of them (particularly bottoms of No. 5 and No.
6) were soaked with oil. We soaked all of them in lacquer thinned, then
took stainless-steel brushes to clean off any deposit that might have
formed. After drying them all out, we put graphite lube on the threads and
installed them to 360inch/lb torque. While the cowl still off, I tried
starting it again.
This time, it will not start AT ALL. I tried about 6 times, each time
cranking for about 10 - 15 seconds each. Heeding you'all's advise, I did
not pump the throttle while not cranking and I tried one and two strokes of
throttle movement on two occasions. I tried booster ON and OFF, Mixture
rich and leaned. After each attempt, I let the engine sit for a minute or
so so as not to build up unburnt fuel in the system.
I suspected flooding or otherwise over-fueling, so after some of the
attempts, I got out and sniffed around the exhaust for AVGAS smell. To my
surprize, I did not smell much at all. Admittedly, it was a bit of a windy
day but I was standing downwind and I would have smelled fuel.
I should note that I got it to make the "Brr" noise once indicating there
was some ignition but it did not catch.
My fuel system is a fairly standard FG setup with sump and electrical
boost pump. I have the Franklin fuel pump AD done with a bypass with a
check valve. I do not have the primer yet (parts are on order).
The sump pickup is on the bottom as factory specifies and the fuel line
run "uphill" for a bit to about halfway between the carry-through spar and
fuselage bottom where the boost pump, flow sensor and fuel filter is
located. From there, the line goes through the firewall, to a T-fitting
that separates the bypass line and the feed to the mechanical pump. After
the pumpl, it will re-merge and drop down to the Carb. The fuel pressure
sensor is located at the Carb.
When I turn on the boost pump prior to cranking, the fuel flow and
pressure both indicate activity indicating that fuel is flowing.
I am really scratching my head as to what may be causing this difficulty
and how I could debug the problem. With the electrical system, I can go
around poing each connections with a multimeter and what not but I am at a
loss as to what to do with the power plant.
Somehow, I am suspecting that the fuel is not getting to the carb, based
on the absense of fuel smell in the exhaust stack after unsuccessful tries.
Is that a fair assumption?
One thought that did occur this week was to run the electric boost pump
until I see fuel pressure and continue running until I see the flow drop to
near 0 indicating that the bowl on the Carb is full and the float has tipped
the fuel supply off. Perhaps the fuel line is filled with air while the
aircraft sits on the ground.
Is this a sound reasoning?
Hiroo
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From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Laurence Coen
Sent: Tuesday, September 05, 2006 8:47 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Franklin
Hiroo,
Here's how I did it. I made my primer injectors form two AN822-2D elbows
that are screwed into the bottom center primer port on each manifold. The
original Franklin primer manifold injects fuel at three points in each
manifold. The threads on the manifold plug are straight and not pipe. You
can convert them to pipe by running a pipe tap in a few turns because the
thread pitch and diameter are a match. I made a spray nozzle by tapping the
inside of the AN822-2D for a short brass screw and drilling it lengthwise
with a #60 drill. I used #2 Permatex on the threads so it couldn't vibrate
loose. You need to tee into your fuel system on the pressure side of your
electric fuel pump. This goes to a solenoid valve which is in turn plumbed
to the injectors. You will need wire and a push button switch to operate
the solenoid valve.
From Aircraft Spruce
Solenoid valve P/N 05-29823
elbows AN822-2D
tee AN826-2D
nipple AN816-2D
nuts AN818-2D
sleeve AN819-2D
1/8" aluminum tubing
----- Original Message -----
From: Hiroo Umeno
To: Velocity Aircraft Owners and Builders list
Sent: Monday, September 04, 2006 11:21 PM
Subject: Re: REFLECTOR: Franklin
Steven did warn me about the induction fire danger with pumping the
throttle. He told me that I can pump exactly once.
It seems to me that a primer is a virtual necessity with one of these
engines. Does anyone have a part list for the setup? I'd like to order the
parts and get started on it next time when I head out to the hangar. I
imagine it is a fairly simple setup.
Hiroo
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From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of MikeWatsonSpg at cs.com
Sent: Monday, September 04, 2006 12:21 PM
To: reflector at tvbf.org
Subject: REFLECTOR: Franklin
Hiroo,
What ever you do, please do not pump the throttle to
start the engine. Both Denis and I had fires while trying
to start our engines at F. 40
I was lucky, no damage. Denis Miller cowls and firewall were
burnt very badly. After that incident, we installed the
fuel injector rails with a solenoid. Now our procedure
for starting is the same as Larry stated. Follow Larry's
suggestions and you will be OK.
The Franklin is a great engine, it takes a lot of abuse,
Idles like a dragster and runs as smooth as silk between
2500 and 2700 RPM. Mine has given me excellent service
for nine years now.
Mike W.
SERG Franklin/IVO Electric CS
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