Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Tue, 13 Aug 2002 08:48:54 -0400
Message-ID: <redirect-1687037@logan.com>
From: "Ted Stanley" <ted@vineyard.net>
Subject: Carburetor Engine Starting
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Under the thread of fuel pump use I noticed that Dick Alden remarked about
priming using the throttle and how a friend of his almost made toast out of
his airplane so I thought I would add a little something.

NEVER use the throttle to prime an engine with an updraft carburetor.
Admonish anyone you see doing it, you may save an airplane or it's
passengers from burning up.

"Pumping" the throttle causes fuel to squirt out of the carburetor's
accelerator pump up into the engine. That's fine except gravity drains the
fuel back down where it can puddle and a backfire through the carburetor
will likely ignite it and create an induction system fire.

Here's what has worked for me based on several thousand hours of flying a
Piper Archer (Lycoming O-360):

Get ready to start the engine.

Start the engine turning.

SMOOTHLY and briskly "pump" the throttle from full closed to full open once
or twice ending with the throttle closed or nearly so. DO THIS ONLY WHILE
THE ENGINE IS TURNING !! This draws the accelerator pumped fuel into the
engine. The engine will fire right up without a fuss providing the rest of
the engine is in good shape (spark plugs, ignition timing, compression,
etc.)

The above procedure works nicely on a cold engine in moderate temperatures.
In colder weather the engine primer may be required.

The primer is normally a manual plunger type pump which forces fuel through
several primer nozzles near the intake valves. One or more primer nozzles
can become plugged which may result in hard starting. Check and clean them
occasssionally. Check for leaks after you do so.

The trick to cold weather starting is to pump the primer several times, WAIT
30 seconds or so for the fuel to evaporate inside the intake manifold, then
proceed with the warm weather starting technique outlined above. Be sure to
lock the primer plunger in place after using it. Failure to do so allows
fuel to siphon through the primer pump into the engine causing a rich
mixture at idle.

Happy Motoring,

Ted Stanley - A&P-IA
Direct Flight, Inc.
Lancair IV - in progress