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09-25-2018, 09:20 AM
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Join Date: Apr 2013
Location: Lincoln, CA
Posts: 14
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IO-390 hard second start
Good Morning all,
Almost finished with an RV-14A. The IO-390 fire up good on the first start. 1 sec fuel boost pump, 1/4 inch throttle and mixture back about 1 inch. Its the second start that is the problem. I've read the different post about hard starting and none of those techniques are working for me. I've tried the hot start procedure and the flooded start procedure. Engine never kicks over.
1. How far back does the mixture control have to be to be considered lean? Can this be described in inches or do I have to run the engine to find that position?
2. Not currently get a fuel flow reading on the Dynon EFIS, I have to trace the wires from the cube to the VPX and the EFIS. The engine is not using the fuel flow reading for anything, is it?
Any suggestions would great greatly appreciated.
Thanks
Tim W.
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09-25-2018, 09:30 AM
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Join Date: Dec 2007
Location: Dogwood Airpark (VA42)
Posts: 2,596
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Many threads on this. Short summary:
Cold start:
- Throttle cracked open, Mixture at cutout.
- Boost pump on.
- Mixture full rich for about 5 seconds, then back to cutout.
- Crank, advance mixture when engine fires.
Hot Start:
- Throttle cracked open, mixture at cutout.
- Boost pump on.
- Crank engine, advancing mixuture slowly after engine fires.
At idle, mixture as lean as it will go and still have the engine running.
Carl
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09-25-2018, 10:54 AM
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Super Moderator
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Join Date: May 2005
Location: Locust Grove, GA
Posts: 2,626
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I have found that it starts better hot WITHOUT the boost pump being on. Throttle just a little bit open, and SLOWLY advance the mixture as it starts to fire. Hasn't let me down yet.
Vic
__________________
 Vic Syracuse
Built RV-4, RV-6, 2-RV-10's, RV-7A, RV-8, Prescott Pusher, Kitfox Model II, Kitfox Speedster, Kitfox 7 Super Sport, Just Superstol, DAR, A&P/IA, EAA Tech Counselor/Flight Advisor, CFII-ASMEL/ASES
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Author "Pre-Buy Guide for Amateur-Built Aircraft"
www.Baselegaviation.com
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09-25-2018, 11:18 AM
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Join Date: Nov 2006
Location: Saint Simons Island , GA
Posts: 1,523
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Just start it
Like Vic, I don?t move anything but just barely advance the throttle. No pumps, no mixture movement, no squirming, no sweating.
Mags HOT and crank it. Mixture in when it fires and go fly.
I?ve used this technique for a very long time on Lycomings. Never failed me yet.
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Jerry "Widget" Morris
RV 8, N8JL, 3,000+ hours on my 8.
VAF #818
Saint Simons Island, GA. KSSI
PIF 2008, 2009, 2010, 2011,2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020
 I just wish I could afford to live the way I do
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09-25-2018, 11:29 AM
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Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,297
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The "hot start" procedures discussed here are for engines at full operating temps and with an enclosed cowl. The engine heat in the closed cowl causes fuel boiling after a few minutes and therefore a special technique for starting.
If you are doing short runs without a cowl, as I am guessing you might be, the hot start procedure is not necessary and will likely make for difficulty in starting. Short runs even with a cowl will not produce enough heat to cause fuel boiling.
I suggest doing your starts with mixture full rich until you have some experience, before guessing what is correct for starting. FYI, most engine starts done properly are on the idle circuit and no need for trying to adjust mixture with the red knob. mixture is done via the idle mixture screw on the servo. HOT start procedure is the exception.
You should quickly adjust the idle mixture, as this is often not done at the factory and a poor idle mixture can create difficulty in starting.
A warm (not Hot), uncowled engine should start easily with the throttle cracked a 1/4" and mixture full rich. No boost pump shot required once the engine is even a little bit warm. Doing this on a warm engine will make starting difficult.
Larry
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Last edited by lr172 : 09-25-2018 at 11:43 AM.
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09-25-2018, 12:15 PM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,516
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Quote:
Originally Posted by vic syracuse
I have found that it starts better hot WITHOUT the boost pump being on. Throttle just a little bit open, and SLOWLY advance the mixture as it starts to fire. Hasn't let me down yet.
Vic
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Quote:
Originally Posted by RV8iator
Like Vic, I don?t move anything but just barely advance the throttle. No pumps, no mixture movement, no squirming, no sweating.
Mags HOT and crank it. Mixture in when it fires and go fly.
I?ve used this technique for a very long time on Lycomings. Never failed me yet.
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+1, +1 and I found even moderate mix will kill it and flood. YMMV
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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09-25-2018, 01:13 PM
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Join Date: Sep 2013
Location: Rancho San Lorenzo
Posts: 885
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Quote:
Originally Posted by BillL
+1, +1 and I found even moderate mix will kill it and flood. YMMV
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+1, +1, +1
No fancy dances or swapping throttle and mixture back and forth when firing needed.
__________________
RV-8
(a few more airplanes too)
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09-25-2018, 10:01 PM
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Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
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Quote:
Originally Posted by vic syracuse
I have found that it starts better hot WITHOUT the boost pump being on. Throttle just a little bit open, and SLOWLY advance the mixture as it starts to fire. Hasn't let me down yet.
Vic
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I agree with Vic
I never use the boost pump starting any of our fuel injected airplane, when hot (or warm even).
If you have the standard kit supplied Andair fuel pump, it is a rather high volume pump and it will be flooding the engine before you get it to start.
Throttle cracked about 1/4", mixture fed in slowly while cranking at a feed rate such that it would take 5-6 seconds to go from ICO to full rich. Will usually fire when about 1/2 way in.
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Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.
Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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09-26-2018, 04:45 PM
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Join Date: Apr 2013
Location: Lincoln, CA
Posts: 14
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Very cool,
Started right up. Thanks for the help!
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