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cjaviator(at)gmail.com
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 Posted: Sat Apr 06, 2013 3:14 pm Post subject: CJ starting/mag drop issues |
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Hi all.
Had a CJ through for an annual recently and we noticed a couple of irregularities which we have not been able to rectify as yet...
1) #1 mag exhibits a constant mag drop throughout all RPM ranges of about 100 RPM and nearly stops at idle.
Initially we focussed on the mag drop as although not alot, something was not quite right. We changed the plugs for new items (no effect); retimed the mag (no effect); changed the coil (no effect); and somewhat grasping at straws, changed the mags from side to side.
This seemed to fix the fault and the owner took the aircraft away but the fault seems to have returned. Any ideas out there? We are thinking it must be a plug lead. I know many of you have experienced plug lead woes in the past but in 15 years of operating CJ's in a dry environment I have never had a problem before. (aircraft has standard factory harness and leads but is operated in a wetter environment than I am used to).
2) Aircraft can be hard to start. Intitally we thought this was related to the mag problem but it seems to be more fuel related. Initally after the annual I could not get it started and thought it was the part-worn set of plugs we had just installed. I swapped them out for the old plugs with no effect and then realised the aircraft had been parked on a slope for some hours with minimal fuel in it... turned the aircraft 180 degrees and sure enough she started first go.... a-ha - must have been no fuel to carb I thought....
Alas no.... still exhibits hard starting from time to time.... will turn and turn with no sign of life and then exhibit quite a violent ignition event on one or two cylinders. Sometimes it seems it is over-primed (lots of fuel out of the manifold drain) but other times under-primed. Other times it will start happily and repeatedly. Engine being cold or at operating temp does not seem to matter.
As seen above mag timing has been checked. Additionally we have checked shower of sparks (OK) and primer line (OK) but are a bit lost as to where to go now. Next step might be to pull the primer atomiser from the blower case and check it is not blocked/damaged.
Perhaps the two symptoms are related - perhaps not?
Any ideas/help on this gratefully accepted!
Regards, Jay
New Zealand
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pfstelwagon(at)earthlink.
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| Posted: Sat Apr 06, 2013 4:24 pm Post subject: CJ starting/mag drop issues |
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1. Go with the auto plug conversion!! The original plug leads are old and not great to begin with.
2. Remove the primer line at the engine fitting, put it in a container and work the primer. Saw a CJ with a cracked line on the suction side of the primer, made a great air pump but no fuel. Had the same starting problems.
Frank
CJ6-A
[quote] ---
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jan.mevis(at)informavia.b
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| Posted: Sun Apr 07, 2013 12:36 am Post subject: CJ starting/mag drop issues |
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I concur with that!
I also had large drops on the mags, changed plugs several times, no good.
Replacing the old ignition wires is not really an option.
All these problems went away after installing Dennis' auto plug kit on my plane.
And the car spark plugs (I use NGK) are not only much better, but also a lot cheaper.
Jan
From: Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)>
Reply-To: "yak-list(at)matronics.com (yak-list(at)matronics.com)" <yak-list(at)matronics.com (yak-list(at)matronics.com)>
Date: Sunday 7 April 2013 02:21
To: "yak-list(at)matronics.com (yak-list(at)matronics.com)" <yak-list(at)matronics.com (yak-list(at)matronics.com)>
Subject: Re: Yak-List: CJ starting/mag drop issues
1. Go with the auto plug conversion!! The original plug leads are old and not great to begin with.
2. Remove the primer line at the engine fitting, put it in a container and work the primer. Saw a CJ with a cracked line on the suction side of the primer, made a great air pump but no fuel. Had the same starting problems.
Frank
CJ6-A
[quote] ---
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gill.g(at)gpimail.com
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| Posted: Mon Apr 08, 2013 8:53 am Post subject: CJ starting/mag drop issues |
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<![if !supportLists]>1) <![endif]>Make sure both mags have the same advance.
<![if !supportLists]>2) <![endif]>We had a plugged primer nozzle that caused similar problem.
Gill
From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of Jay McIntyre
Sent: Saturday, April 06, 2013 4:12 PM
To: yak list
Subject: CJ starting/mag drop issues
Hi all.
Had a CJ through for an annual recently and we noticed a couple of irregularities which we have not been able to rectify as yet...
1) #1 mag exhibits a constant mag drop throughout all RPM ranges of about 100 RPM and nearly stops at idle.
Initially we focussed on the mag drop as although not alot, something was not quite right. We changed the plugs for new items (no effect); retimed the mag (no effect); changed the coil (no effect); and somewhat grasping at straws, changed the mags from side to side.
This seemed to fix the fault and the owner took the aircraft away but the fault seems to have returned. Any ideas out there? We are thinking it must be a plug lead. I know many of you have experienced plug lead woes in the past but in 15 years of operating CJ's in a dry environment I have never had a problem before. (aircraft has standard factory harness and leads but is operated in a wetter environment than I am used to).
2) Aircraft can be hard to start. Intitally we thought this was related to the mag problem but it seems to be more fuel related. Initally after the annual I could not get it started and thought it was the part-worn set of plugs we had just installed. I swapped them out for the old plugs with no effect and then realised the aircraft had been parked on a slope for some hours with minimal fuel in it... turned the aircraft 180 degrees and sure enough she started first go.... a-ha - must have been no fuel to carb I thought....
Alas no.... still exhibits hard starting from time to time.... will turn and turn with no sign of life and then exhibit quite a violent ignition event on one or two cylinders. Sometimes it seems it is over-primed (lots of fuel out of the manifold drain) but other times under-primed. Other times it will start happily and repeatedly. Engine being cold or at operating temp does not seem to matter.
As seen above mag timing has been checked. Additionally we have checked shower of sparks (OK) and primer line (OK) but are a bit lost as to where to go now. Next step might be to pull the primer atomiser from the blower case and check it is not blocked/damaged.
Perhaps the two symptoms are related - perhaps not?
Any ideas/help on this gratefully accepted!
Regards, Jay
New Zealand
| Quote: | | http://www.matronics.com/Navigator?Yak-List |
01234567
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dsavarese0812(at)bellsout
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| Posted: Mon Apr 08, 2013 12:17 pm Post subject: CJ starting/mag drop issues |
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A couple of thoughts.
- First, have you removed the starting coil wire from the left magneto
and tested it to ground to see if it is actually producing a solid
spark? It should be able to jump about 3/8" to ground. You will need
someone in the cockpit to assist. Be sure to deplete all the air in the
system forward of the main air valve (make sure the air is off) by
squeezing the brake lever until no "woosh" sound can be heard. Have the
person on the ground hold the starting coil wire about 3/8" or so from
ground using a pair of insulated pliers. Be sure to hold the insulated
part of the pliers only. Or you can position the starting coil wire so
it is about 3/8" from ground. Then turn on the Battery and the
Ignition switches. Have the person in the cockpit press the START
button. The starting coil wire should easily jump from the wire to
ground. The engine will not rotate because you have depleted the air
forward of the main air valve. If the starting coil wire does not arc
to ground, you should check the points in the starting coil AND possibly
replace the starting coil wire.
The starting coil wire very often deteriorates and cracks. Thus when
the start button is pressed, the spark from the starting coil will never
make it to the magneto cap because it is arcing to ground inside the
braided shield. This is a very common problem.
- While you have the magneto cover and cap off on the left side, do
check the point gap. It should be .25 to .35 mm or .0010 to .0014.
Ideally the point gap should be .3 mm or .0012. If you must adjust the
point gap on either or both mags, you must go back and check the
timing. I'm sure you already know the mag timing is based on the number
stamped in the mag cover mating surface and correlated to the Housai
timing chart. If both mags have the same number stamped on them, the
mags can be synchronized. If the numbers do not match, the mags can not
be synchronized and set to its own specified timing.
If you need an illustration of how to set the points or even the fine
timing adjustment, let me know and I will send you the illustration.
Dennis
A. Dennis Savarese
334-285-6263
334-546-8182 (mobile)
www.yak-52.com
Skype - Yakguy1
On 4/6/2013 6:11 PM, Jay McIntyre wrote:
| Quote: | Hi all.
Had a CJ through for an annual recently and we noticed a couple of
irregularities which we have not been able to rectify as yet...
1) #1 mag exhibits a constant mag drop throughout all RPM ranges of
about 100 RPM and nearly stops at idle.
Initially we focussed on the mag drop as although not alot, something
was not quite right. We changed the plugs for new items (no effect);
retimed the mag (no effect); changed the coil (no effect); and
somewhat grasping at straws, changed the mags from side to side.
This seemed to fix the fault and the owner took the aircraft away but
the fault seems to have returned. Any ideas out there? We are thinking
it must be a plug lead. I know many of you have experienced plug lead
woes in the past but in 15 years of operating CJ's in a dry
environment I have never had a problem before. (aircraft has standard
factory harness and leads but is operated in a wetter environment than
I am used to).
2) Aircraft can be hard to start. Intitally we thought this was
related to the mag problem but it seems to be more fuel related.
Initally after the annual I could not get it started and thought it
was the part-worn set of plugs we had just installed. I swapped them
out for the old plugs with no effect and then realised the aircraft
had been parked on a slope for some hours with minimal fuel in it...
turned the aircraft 180 degrees and sure enough she started first
go.... a-ha - must have been no fuel to carb I thought....
Alas no.... still exhibits hard starting from time to time.... will
turn and turn with no sign of life and then exhibit quite a violent
ignition event on one or two cylinders. Sometimes it seems it is
over-primed (lots of fuel out of the manifold drain) but other times
under-primed. Other times it will start happily and repeatedly. Engine
being cold or at operating temp does not seem to matter.
As seen above mag timing has been checked. Additionally we have
checked shower of sparks (OK) and primer line (OK) but are a bit lost
as to where to go now. Next step might be to pull the primer atomiser
from the blower case and check it is not blocked/damaged.
Perhaps the two symptoms are related - perhaps not?
Any ideas/help on this gratefully accepted!
Regards, Jay
New Zealand
*
*
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cjpilot710(at)aol.com
Guest
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| Posted: Mon Apr 08, 2013 4:45 pm Post subject: CJ starting/mag drop issues |
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This is a good idea. Pappy
Sent from AOL Mobile Mail
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