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Thread: 912A cold start issue

  1. #1

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    Default 912A cold start issue (Non issue now!)

    Hi.

    I´m very happy with my 912 (KF-III) in all respect except on the first start of the day it takes a really long start to get it running

    I take it out of a well heated hangar and have to start 15-20 seconds before it lights up. When it fires it runs silk smooth.

    I have tried various settings on the throttle and choke and it makes no difference. The battery is new at it gets very good rpm´s during start.

    It seem it´s not getting fuel. But the fuel in the carb bowl can´t evaporate over one night, can it?

    What´s wrong, do you guy´s have a primer to get the 912 to start right up or is this normal? This is mostly irritating, it always starts in the end but I want engines to fire up immediately.

    I´m using AVGAS by the way.

    Thanks.
    Walter
    Last edited by Iceflyer; 06-23-2010 at 02:50 AM. Reason: problem solved

  2. #2
    Senior Member Dave S's Avatar
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    Default Re: 912A cold start issue

    Hi Walter,

    Not going to say I know what the problem is; but, here are a couple items to check. You mentioned the hangar is warm, but you didn't say what "warm" is. On my 912S if the soak temperature if 10 degrees C or better - the engine should start right off if everything is well.

    1) The throttle has to be closed. A cold start will take longer if the throttle is partially cracked open. Throttle position and throttle stops and carb balance can be issues.

    2) The manual choke needs to have both choke valves close completely. It can happen where the linkage gets a bit sticky; or some other mechanical interference keeps one or the other or both from closing completely - takes two people to check this out - if the cables are set so one choke closes first, the other can remain open a bit, slowing down the start up.

    Sincerely,

    Dave S
    St Paul MN, USA

  3. #3

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    Default Re: 912A cold start issue

    Hi thanx.

    The hangar is very warm. heating is cheap here because we have hot thermal water pouring out of the ground. Temps in the hangar are about 24-25°c or 75°F.

    ok I´ll check the choke valves and and do the next start with the throttle closed. Hope it works

  4. #4
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    Default Re: 912A cold start issue

    The choke (starting carb) will ONLY function with the throttle completely closed.
    If for some reason that does not cure your problem (which I am sure it will) you could go to a primer system as I have on mine. Two squirts and BOOM it starts every time.
    Dick

  5. #5
    Senior Member cap01's Avatar
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    Default Re: 912A cold start issue

    dick , do you have a choke installed also ? whats your start proceedure using the primer ?
    chuck
    kitfox IV 1050
    912ul warpdrive
    flying B , yelm, wa

  6. #6
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    Default Re: 912A cold start issue

    Chuck,
    I do not have a choke.I purchased the aircraft in Mass The former owner had removed the chokes and installed the primer system. He said the cold weather was the reason he did this. His theory was confirmed when I attended Rotax school at Lockwood. The instructor mentioned that a primer could make it easier to start in cold weather.
    As I live in Fl I was going to remove it and install the chokes.In fact I bought all the cables,fittings,etc but the engine starts so easy with the primer,I haven't done it and probably won't.
    My normal procedure is to give 2-3 squirts of primer then open the throttle 2 turns from fully closed (I have a Vernier throttle) and hit the starter. I barely get more than 1/2 blade of movement before it is running.( around 1600-1800 rpm) When it is cold,for here ( 20's-30's),I may have to add another squirt of fuel.
    On occasion(very rarely) I have flooded it with too much fuel from the primer. In that case I open the throttle fully, crank the engine and when it fires,immediately to idle. If you had individual mag switches,which I don't ,you could unload the engine from this excess fuel by turning the mags off,wide open throttle,crank the engine to suck air thru it for a few seconds, throttle idle ,mags on and restart.
    Dick Maddux
    Fox4
    912UL

  7. #7
    Senior Member cap01's Avatar
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    Default Re: 912A cold start issue

    thanks dick , i have the choke set up but i think i have most of the pieces for the primer that hasnt been installed . actually havent had too much trouble starting when it was cold . it got pretty chilly up here on the left coast last winter , low teens but had it preheated before any starts and that worked good .
    chuck
    kitfox IV 1050
    912ul warpdrive
    flying B , yelm, wa

  8. #8
    Super Moderator Av8r3400's Avatar
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    Default Re: 912A cold start issue

    Starting my 912UL with the choke (I don't have a primer), all winter, in temps down to zero, while ski flying never resulted in a failed start.

    I hangar my plane and preheat with a cube heater and an insulated cover the cowl, but while ski flying sometimes parked for a couple of hours at a time, the engine will completely cool down to the ambient temperature. It has never failed to start for me.


    For the record, the carbs on a 912 do not have chokes. They have an enrichment circuit. This is why the throttle must be closed (completely) for this circuit to work.
    Av8r3400
    Kitfox Model IV
    The Mangy Fox
    912UL 105hp Zipper
    YouTube Videos

  9. #9

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    Default Re: 912A cold start issue

    Hi thanx guy´s

    I did not realize that the throttle had to be closed completely or for that matter that the carbs don´t really have a choke Just shows what happens when guy´s like me who are to lazy to build a Kitfox himself starts flying them.

    We´ll anyhow. Now it fires up right away everytime. I just make sure the throttle is pulled completely closed. I actually have to pull back on the throttle (vernier type). I wonder if it would not be better to adjust the idle lower and then manually adjust to proper idle speed (1800 ) when it starts?

    Another thing happened to me today.. Carb ice!

    Do you guy´s regularly get carburator ice?

    I was at 4000´ and about 4-5°c ambient temp. There was no mistaken this for carb ice. I noticed the engine doing a one minor misfire at cruise. The rpm slowly decreased 200-300 rpm three times over a period of about 20 minutes where I corrected with more throttle until I finally figured out that it was not quite normal to happen.. sorry guy´s I fly big turbines for a living

    When I turned carb heat on the rpm increased within seconds about 600 rpm and when I turned carb heat off after a few min the rpm´s increased another 150-200 rpm.

    Do you usually fly with some carb heat on in conditions with visible moisture and close to freezing temps or is this uncommon to happen in the 912?

    Nobody told me to watch out for carb ice and this was not particularly scary I just feelt a little stupid for not figuring out right away what was happening.

    photo about 30min before carb ice

  10. #10
    Senior Member Slyfox's Avatar
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    Default Re: 912A cold start issue

    you have a vernier throttle so it would be easier to lower the idle to lower than 1800 and use that lower idle to your advantage. Meaning you can start the engine with the throttle pulled all the way back and it will not hit unless you give it a little throttle as you start, this prevents start lock, which usually happens with the uls engine. Next you can now pull back on landing and slow the plane better, just kick in a little throttle on touch down so you don't go below the 1800rpm. Next big one is pulling back on the throttle with turning off the mags will give you a real nice shut off and save the carb sockets. My recomendations are to turn each carb idle screw to the left 1/2 turn on each side and this will give you a good spot for the idle setting. Just remember to keep the idle at 1800 at all times on the ground.

    Carb ice, ya I get it all the time in the winter and lots of moisture, I just make sure and not let it idle to low on approach and not to raise the throttle too fast on a touch and go. Stubbles a little but I'm use to it now.
    steve
    slyfox
    model IV 1200-flying
    912uls
    IVO medium in-flight
    RV7A-flying
    IO-360
    constant speed prop

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