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  #1  
Old 09-25-2018, 10:20 AM
Junk8 Junk8 is offline
 
Join Date: Apr 2013
Location: Lincoln, CA
Posts: 13
Default 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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  #2  
Old 09-25-2018, 10:30 AM
Carl Froehlich's Avatar
Carl Froehlich Carl Froehlich is offline
 
Join Date: Dec 2007
Location: Dogwood Airpark (VA42)
Posts: 1,776
Default

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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  #3  
Old 09-25-2018, 11:54 AM
vic syracuse vic syracuse is offline
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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
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  #4  
Old 09-25-2018, 12:18 PM
RV8iator's Avatar
RV8iator RV8iator is offline
 
Join Date: Nov 2006
Location: Saint Simons Island , GA
Posts: 1,396
Default Just start it

Like Vic, I donít 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.

Iíve used this technique for a very long time on Lycomings. Never failed me yet.
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  #5  
Old 09-25-2018, 12:29 PM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 3,326
Default

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 12:43 PM.
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  #6  
Old 09-25-2018, 01:15 PM
BillL BillL is online now
 
Join Date: Sep 2007
Location: Central IL
Posts: 4,548
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Quote:
Originally Posted by vic syracuse View Post
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
Quote:
Originally Posted by RV8iator View Post
Like Vic, I donít 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.

Iíve used this technique for a very long time on Lycomings. Never failed me yet.
+1, +1 and I found even moderate mix will kill it and flood. YMMV
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  #7  
Old 09-25-2018, 02:13 PM
jliltd jliltd is offline
 
Join Date: Sep 2013
Location: Rancho San Lorenzo
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Quote:
Originally Posted by BillL View Post
+1, +1 and I found even moderate mix will kill it and flood. YMMV
+1, +1, +1
No fancy dances or swapping throttle and mixture back and forth when firing needed.
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  #8  
Old 09-25-2018, 11:01 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 7,863
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Quote:
Originally Posted by vic syracuse View Post
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
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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  #9  
Old 09-26-2018, 05:45 PM
Junk8 Junk8 is offline
 
Join Date: Apr 2013
Location: Lincoln, CA
Posts: 13
Default

Very cool,
Started right up. Thanks for the help!
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