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Engine Starting Problem

RFazio

Well Known Member
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?
 
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.
Don
 
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,
 
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
 
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
 
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.
 
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.
 
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.
 
she is capricious

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



richfazio.jpg
 
I went to the airport last weekend and checked my engine. I checked the timing on the mags. I figured if it was an impulse problem, I would see it in wrong impulse firing time. My mags were timed perfect and the impulse fired at 2 degrees after TDC. I checked the plugs and they looked perfect. I decided to change the four plugs on the left, starting, mag just because it was the easiest point to start at. I got myself a set of four tempest plugs and installed them last night. I pulled the plane out of the hanger with the cowl off and tried to start it. She started instantly. I put the cowl back on and went for a little flight. She started instantly again. I'm ordering another set of four plugs, the tempest plugs look real nice by the way. Thanks for the responces guys.
__________________
Richard Fazio
 
Hard Start!!!!

...I replaced the impulse coupling spring and it worked for a short time then got bad again. I replaced the coupler itself with one from spruce and it worked for 80 or so hrs. I replaced it again and this time I installed one of our oiling kits. Wallah!!!! End of problem. Thanks, Allan...:D
 
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