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Old 04-04-2012, 05:02 AM
RFazio RFazio is offline
Join Date: Jan 2007
Location: LI, NY
Posts: 422
Default Engine Starting Problem

Recently I've been having problems starting my engine. I have a 6 with a new lycoming O-360 A1A. Carb, standard mags and a wood prop. It always started fine. I've got 300 hours on the plane now and I seem to be having trouble starting when cold. I have a vans primer, solinoid and primer lines to three cylinders. I used to prime for a few seconds and she would always start fine. Now it pops, backfires tries to start. Sometimes I think it's just me doing something wrong, priming too much or not enough but it seems to be getting worse. The plugs I changed at about 100 hours. it was running ruff. I haven't touched them since. once running it runs perfect, smooth, maybe 20 or 30 rpm drop on mag check each side. Could it need new plugs or a plug cleaning? I was also thinking maybe the timing is getting out on the mags, I haven't touched them either. Any ideas?
Richard Fazio
RV-6 Slider
FP Wood Prop
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Old 04-04-2012, 05:59 AM
donoltman donoltman is offline
Join Date: Mar 2011
Location: Tulsa, Ok
Posts: 98
Default starting problems

I used to have a O-540 A1A in a Comanche that started having the same symptoms as you. Started perfectly and then the starting problems began to get progressively worse. After ruling out the primer system and plugs we finally pulled the mags and were glad we did. My impulse coupling on new Slicks was coming apart at 500 hours. When I talked to Custom Airmotive about it he indicated that the A1A engine likes to go thru left mags. Not sure whether that's true or not but it was on mine. I think you should pull them and have a look.
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Old 04-04-2012, 08:46 AM
twsurveyor's Avatar
twsurveyor twsurveyor is offline
Join Date: Jan 2005
Location: Ridgetop, Tennessee
Posts: 134
Default Engine Starting Problem

Richard, I have an O-360-A1A with 1300 hrs on it. I don't have a primer system what so ever. Cold start procedure is: fuel pump on, mixture rich, throtle off. Start prop spinning and pump the throtle (once or twice only). Engine usually starts a blade or two after the "pump"!

On my engine, I have noticed that if it becomes hard to start the mag timing is off. Strange as it sounds, if my mags get out of "perfect" time it won't start near as easy.

Hope this helps,
Tommy Walker
Ridgetop, TN (1M5)
RV-6A, N 350 TW
830 Hrs & "Climbing?!
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Old 04-04-2012, 09:30 AM
Ironflight's Avatar
Ironflight Ironflight is offline
VAF Moderator / Line Boy
Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,829

I'm inclined with those suspicious of the impulse coupler - sounds like you are not getting the spark at the right time for start. The impulse coupler can get sticky when it's cold, and if it doesn't work, then you're firing the spark way to early when the engine is just being rotated by the starter.

Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
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Old 04-04-2012, 11:48 AM
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GeneL GeneL is offline
Join Date: Sep 2009
Location: Daytona Beach, Florida
Posts: 121
Default Hard starting

I have the same combination as you and at the same hours my A1A would not start when cold out, no primer. 200 hours on the plugs and the gap was close to .022", closed them down to .016" and it started great. Also at similar times had a condenser fail on the impulse mag, if it would start it would run great. Quick test for the condenser- with engine running turn key (mags) off watch mech. tach let engine spin down to cranking speed (about 300 rpm) then turn impulse mag on, the engine will stumble its way up to about 600rpm then smooth out. Condensers work harder at low rpms. Gene
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Old 04-04-2012, 01:52 PM
hngrflyr hngrflyr is offline
Join Date: Jan 2005
Location: eugene, oregon
Posts: 206

I had the same problem with the O-320 in my RV-6 a couple of years ago. My engine was getting very hard to start, but the mag checks were always good once it was running.

Check your points setting and the condition of the points. The points setting directly effects the strength of the spark. I replaced the points in the left mag. You wouldn't think it was the same engine.
Bob Severns
Eugene, Oregon
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Old 04-04-2012, 04:53 PM
RFazio RFazio is offline
Join Date: Jan 2007
Location: LI, NY
Posts: 422

Thanks so much for the responces guys. I have some work to do this weekend. I would guess that if it was an impulse problem I should be able to tell because the timing of the impulse fire will be off, not at TDC. I think I should check that before I go and pull the mags. Maybe get a better idea of what is going on. The rest would just going over the mags. I think I'll pull the plugs also, and clean and gap for good measure.

Paul, I had the good fortune of talking with Louise at sun & fun about the RV-1. A few of my buddies & I Learned a lot about the plane from her. She is a very well spoken, knowledgeable person and we enjoyed speaking with her.
Richard Fazio
RV-6 Slider
FP Wood Prop
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Old 04-13-2012, 08:20 AM
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rocketbob rocketbob is offline
Join Date: Jun 2006
Location: 8I3
Posts: 3,758

Some food for thought. I recently ferried a RV-6 from AZ back to Indiana, and I had a very hard time starting it. The previous owner basically said "you're not doing it right". Uh, ok. Once it was warm it seemed to start ok. Not good but ok. So one evening last week I went to start it, and ran into the same issue again. So I decided to pull the key switch and remove the jumper to verify the wiring. Bingo. Started on the first blade. Put the jumper back on and switched the mag wires around. Starts like a champ now. The engine has brand-new mags, left mag with the impulse. With the switch wired backwards the impulse-coupled mag was being disabled while cranking. No wonder it wouldn't start! The airplane had been wired this way since 2003 when it first flew.

Please don't PM me! Email only!

Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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Old 04-13-2012, 09:20 AM
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Vlad Vlad is offline
Join Date: Oct 2008
Location: Utah
Posts: 8,440
Default she is capricious

What she needs is a good company. Maybe a fresh set of spark plugs too

Where is N666BK?

Не имей сто рублей, а имей сто друзей.
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Old 04-13-2012, 10:34 AM
664781 664781 is offline
Join Date: Jan 2005
Location: Powder Springs, Ga
Posts: 337
Default Spring

I had to replace the spring in the impulse coupling. Started just fine after that.
Kurt Lohmueller A&P, DAR
Powder Springs, Ga
RV6A "Kurt's Toy" - Flying
RV12 - Flying - Sold
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