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rjdaugh
Joined: 30 Aug 2006
Posts: 195
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 Posted: Mon Jun 29, 2009 10:22 am Post subject: Missing Rotax 912S - A concern? |
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Yeah, I know I am a good straight man.
The $55 spark plug caps didn't solve the missing problem. They are not
loose now, but....
What is a good way to check the fuel pump? Remember it only does this at
altitude and at full throttle.
I am also considering that it may be a problem with winter blend gas. The
change over date here is 1 May, and I may have had some winter gas in it.
Randy
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Randy
Kitfox 5/7 912S
Black Hills, South Dakota |
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KITFOXZ(at)aol.com
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| Posted: Mon Jun 29, 2009 1:03 pm Post subject: Missing Rotax 912S - A concern? |
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Hello Randy,
I was doubting your loose spark plug connectors were the problem when I read it because to actually cause a repeatable miss on that cylinder, both connectors would have to be loose as a goose and arching enough to affect low or no spark at the same exact time on both plugs. I am not saying a loose connector is to be ignored at all, just that by itself, not likely to cause a constant miss-fire at a certain load and altitude.
I don't yet think you have a fuel pump problem either. While a fuel pump problem of not delivering full volume and full pressure would manifest itself at high demand times, a mechanical diaphragm type fuel pump usually does not fail in that way. They usually leak through the diaphragm and failure is pretty bad and it won't deliver fuel at much of a pressure or volume and would be a constant problem at many power settings.
I would like to see you de-pitch your prop a little and repeat your tests. (I wonder what RPM you are turning when the "miss" occurs) Also, I would like to hear that you have totally scrutinized your carb mounting boots to be sure they are not torn or leaking air in any way.
You say the problem goes away when you throttle back a little. Try leaving the throttle put but lower the nose to decrease loading. Does that solve the miss?
As for fuel, be sure every path is clear of dirt and If the above test of lower pitch on the prop doesn't solve it and your carb mounts are squared away, try en richening your carb needles one level.
John
In a message dated 6/29/2009 2:23:09 P.M. Eastern Daylight Time, rjdaugh(at)rapidnet.com writes:
| Quote: | Yeah, I know I am a good straight man.
The $55 spark plug caps didn't solve the missing problem. They are not
loose now, but....
What is a good way to check the fuel pump? Remember it only does this at
altitude and at full throttle.
I am also considering that it may be a problem with winter blend gas. The
change over date here is 1 May, and I may have had some winter gas in it.
Randy
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A Good Credit Score is 700 or Above. See yours in just 2 easy steps!
[quote][b]
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clint_bazzill(at)hotmail.
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| Posted: Mon Jun 29, 2009 1:09 pm Post subject: Missing Rotax 912S - A concern? |
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Randy C
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I don't know what your miss is but have a story. I have a 912ULS C maybe the first Kitfox to have one. I installed it in 1999 C my first real cross country was to Wis C Minn from San Carlos airport near San Fransisco. On the way back landed at Leadville.
I had a engine miss C usually at a higher elevation. It could be taken care of by proper adjustment of manifold pressure C and prop pitch (IVO). I had a small amound of carbon on older type landing gear C it looked like a rich mixture of the engine. It was so new that didn't want to change anything.
When I got back home C dropped the main jet needle one notch. Ran perfect and miss never came back. 1000 hours on engine since then.
Clint
[quote] From: rjdaugh(at)rapidnet.com
To: kitfox-list(at)matronics.com
Subject: RE: Re: Missing Rotax 912S - A concern?
Date: Mon C 29 Jun 2009 12:18:03 -0600
--> Kitfox-List message posted by: "Randy Daughenbaugh" <rjdaugh(at)rapidnet.com>
Yeah C I know I am a good straight man.
The $55 spark plug caps didn't solve the missing problem. They are not
loose now C but....
What is a good way to check the fuel pump? Remember it only does this at
altitude and at full throttle.
I am also considering that it may be a problem with winter blend gas. The
change over date here is 1 May C and I may have had some winter gas in it.
Randy
--
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rjdaugh
Joined: 30 Aug 2006
Posts: 195
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| Posted: Tue Jun 30, 2009 8:21 am Post subject: Missing Rotax 912S - A concern? |
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Thanks John and Clint.
I haven’t changed prop pitch in nearly 3 years. I should have mentioned that I took the fuel line off where it was feeding the fuel pump and had a fuel flow of nearly 20 gpm or about 5 times my normal fuel consumption.
I will try to drop the nose to see what happens. A related observation: At one point I flew for a bit with it missing and at full throttle. It runs, but with much reduced power. I should have noted the exhaust temperatures.
I have a lot of visitors coming soon who want rides. I am not giving any rides until I get this sorted out.
Randy
912S is there, but still missing!
From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of KITFOXZ(at)aol.com
Sent: Monday, June 29, 2009 3:00 PM
To: kitfox-list(at)matronics.com
Subject: Re: Re: Missing Rotax 912S - A concern?
Hello Randy,
I was doubting your loose spark plug connectors were the problem when I read it because to actually cause a repeatable miss on that cylinder, both connectors would have to be loose as a goose and arching enough to affect low or no spark at the same exact time on both plugs. I am not saying a loose connector is to be ignored at all, just that by itself, not likely to cause a constant miss-fire at a certain load and altitude.
I don't yet think you have a fuel pump problem either. While a fuel pump problem of not delivering full volume and full pressure would manifest itself at high demand times, a mechanical diaphragm type fuel pump usually does not fail in that way. They usually leak through the diaphragm and failure is pretty bad and it won't deliver fuel at much of a pressure or volume and would be a constant problem at many power settings.
I would like to see you de-pitch your prop a little and repeat your tests. (I wonder what RPM you are turning when the "miss" occurs) Also, I would like to hear that you have totally scrutinized your carb mounting boots to be sure they are not torn or leaking air in any way.
You say the problem goes away when you throttle back a little. Try leaving the throttle put but lower the nose to decrease loading. Does that solve the miss?
As for fuel, be sure every path is clear of dirt and If the above test of lower pitch on the prop doesn't solve it and your carb mounts are squared away, try en richening your carb needles one level.
John
In a message dated 6/29/2009 2:23:09 P.M. Eastern Daylight Time, rjdaugh(at)rapidnet.com writes:
| Quote: |
Yeah, I know I am a good straight man.
The $55 spark plug caps didn't solve the missing problem. They are not
loose now, but....
What is a good way to check the fuel pump? Remember it only does this at
altitude and at full throttle.
I am also considering that it may be a problem with winter blend gas. The
change over date here is 1 May, and I may have had some winter gas in it.
Randy |
A Good Credit Score is 700 or Above. See yours in just 2 easy steps!
0123456789
[quote][b]
| | - The Matronics Kitfox-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kitfox-List |
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_________________
Randy
Kitfox 5/7 912S
Black Hills, South Dakota |
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propellerdesign(at)tele2.
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| Posted: Tue Jun 30, 2009 9:10 am Post subject: Missing Rotax 912S - A concern? |
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Have flown 2 airplane with valve sticking, both O-200 engines but diffrent aircraft, all of a sudden it loose power and start to shake, then it go away.
Jan
[quote] ---
| | - The Matronics Kitfox-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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Av8r3400
Joined: 22 Sep 2008
Posts: 83
Location: North Central Wisconsin (KRRL)
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| Posted: Tue Jun 30, 2009 9:21 am Post subject: Re: Missing Rotax 912S - A concern? |
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I'm a nooby so I know very little, but one thing that was pointed out to me on my 912UL is the braided lines coming from the flywheel (pickup coils) to the CDI boxes. If they are tight, they can pull loose from one or both ends only under high torque load (high power) when the rubber engine mounts flex.
Maybe something else to look at?
| | - The Matronics Kitfox-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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Thanks,
Av8r3400
Kitfox Model IV-1200 W/912UL & IVO
Kitfox Model IV-1050 W/912UL & Warp
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