REFLECTOR: IO-550N Hot Start Procedure

[Bob Jackson (JaxTech)]

Thanks, Scott - I'll give your method a try!  Bob

 

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From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Scott Derrick
Sent: Sunday, August 14, 2011 2:41 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: IO-550N Hot Start Procedure

 





both knobs to the firewall,  3 seconds of electric fuel pump. No more than
that!

            Would that equate to  seconds HIGH or LOW boost with the
standard Velocity 'Dukes' boost pump?

3 seconds low boost.  I only use high boost for cold starting or vapor lock.




pull the throttle out half way.
start cranking, if it doesn't hit in about 3-5 seconds of cranking, slowly
start pushing the throttle in. 

You can try this twice though the second time you have to reduce the prime
time to 1-2 seconds

            I only use 2 seconds of HIGH boost as above for a cold start, so
your hot start method sounds like 

what I would call a 'flooded' approach.  3 seconds of boost prime sounds
like it would definitely

clear the vapor out of the fuel injector lines, which I believe is the main
issue making hot starts hard.

But are you worried about the excess fuel washing all the oil off the
cylinder walls and rings, or is 

that not even an issue to worry about?  


Your mostly priming to get a bit of cooler fuel in the injector lines,
secondary is priming.  I never worry about washing fuel off the cylinder
walls.  I think thats a red herring. THe injectors spray into the induction
system not the cylinders.  Less than a second after starting, oil is
splashing around in the crank case to provide plenty of lubrication.

If you flood it: 

            How do you know you've flooded it - just the fact that it
doesn't start in 8 or 10 seconds?  A basic

            problem I have is knowing whether I'm giving it too little or
too much fuel when its hot.

My philosophy for hot starts is you need very little priming fuel.  And it
is very easy to flood a 520/550 when its hot.  My indication of a flooded
engine is , I primed it and it is not firing after 10 seconds of cranking.
Fuel running out of my induction drain is another indicator, though thats
hard to see when your inside the plane.  I think most hot start problems are
from priming too much.  

My biggest worry when hot starting, and it doesn't catch on that first
prime/crank session, is frying the starter by cranking too long.  The
starter is already hot and its amazing how much hotter it can get if you sit
on the starter button a long time.



Scott




-- 
Eighty percent of success is showing up.
Woody Allen
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