Fw: REFLECTOR: Help -- Franklin -- stuck in SLC

[Ronnie Brown]

I added a couple of comments to Scott's excellent suggestions:


----- Original Message ----- 
From: "Scott Derrick" <scott at tnstaafl.net>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Sunday, October 10, 2004 10:34 AM
Subject: RE: REFLECTOR: Help -- Franklin -- stuck in SLC


|
| >
| >Are you sure your air filter is not clogged?  If you have a manifold
gauge,
| >does it show close to 29 inches while cranking?
|
| Air:
|
| You won't see 29 inches at 4300 ft, but you should see about 24.5 inches.
|
| You could remove the air filter and try starting but I think a visual
| inspection of the intake system would probably verify you haven't sucked
up
| a rag or a bird hasn't built its nest over night in it.
|
| Verify you have about 24 inches with a short 3 second cranking.
|
| Sounds like no spark or no fuel.
|
| Spark:
|
| Its tough to check the plug firing on a V. Get a volt/OHM meter.   Turn
off
| the MAGs and check at the point on the mags that they are grounded.   Now
| turn them on and verify they are not grounded(open).  If possible
| disconnect the starter relay, have somebody hold the key in the "start"
| position and verify they are still not grounded.  Its possible for the Mag
| internal wire to break open but highly unlikely both mags would go south
in
| this way.

Actually, by ungrounding the P leads on the mags and attaching an ohm
metter, you will still see about 3 ohms (pretty heavy windings in the
coils).  On a cheap ohmmeter, it might look like a short.  But if you have
an ohm meter that can read tenths of an ohm you should be able to see the
difference between grounded and "open".


| You can take all 6 plugs out, lay one the cylinder hooked to its
| wire.  Now lay on the wing from the front in a secure fashion  and have
| somebody crank the engine through.  You should see a weak spark.  Do this
| out of the direct sunlight.

Actually, you should be able to see the spark by turning the engine over by
hand (be sure ALL six plugs are out, and listening for the impulse coupling
snap at the number 1 firing position.  You should see a spark when the
coupling snaps.

While you have all six plugs out, you should go ahead and verify that the
timing is correct.  You may need to get an A&P to bring his buzz box and
have him verify the timing.  You can actually do this by listening to the
impulse coupling after verifying that you have a spark.  Find the number one
cylinder, turn the engine over until you get compression on #1 cylinder by
holding your finger in the plug hole and turning the engine by hand until
you get strong air pressure on your finger.  Then back the engine up by a
half turn, then turn the engine in the correct direction.  You should hear
the impulse coupling snap right at top dead center.

| Fuel:
|
| An easy way to verify your getting fuel is to try starting normally with
| the top or bottom cowl off.  Be liberal with the fuel controls.   If no
| start(sounds of firing) after a couple 20 second try's immediately pull a
| top plug.  If its not wet you are not getting any fuel.
|
|  From there its a process of elimination.  Any clear view filters you can
| visually inspect.  I would start at the carburetor and work back to the
| fuel sump.  Is there a screen or built in filter on the carburetor?
Ground
| both mags with wires and clips to prevent ignition. Disconnect fuel line
at
| carb, turn on aux pump. If it flows now try turning the engine using the
| mechanical pump, verify flow.  If it flows you have a carburetor problem,
| if not the problem is up the line.  Go the next place in the fuel system
| towards the tanks and disconnect and try again.
|
| ***Be sure to have your extinguisher real handy just in case. ***
|
| Scott
|
| "Those who sacrifice freedom to get security, deserve neither."
| - Benjamin Franklin
|
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