In a previous post I asked what folks thought about my going it alone after a dozen or so successful buddy cord landings. My instructor and I aren't going to be able to get together for a few weeks.

I felt pretty confident, so headed off to the public (non-club) field where I flew it just fine.

However, I made about 4 landing attempts, but on each one, whenever I throttled back to idle for final approach, the engine died. I got her in fine, though rather ugly on the first three. The last was a little worse, as I was trying give myself a longer approach, and actually was a lot further out than I thought. Once again, the motor quit on my turning into final, and as I started to glide her in, wap, a tree! Fortunately, she was flying quite slow at the time, and hit the top of the tree. It took me about a half an hour and a bunch of scratches and nicks, but I got the plane, and she's no worse for wear, you'd never know it crashed. I guess I haven't gotten the depth perception part down quite yet.

But anyway, on to my question. When the plane was on the ground, I could rev the engine all the way up, no problem, and idle fine as well. When I simulated a flight, by revving full throttle for a minute or so, then half throttle for a minute or so, then cut the throttle all the way back, the engine seemed fine.

But, every time in the air, as I turned into the base leg, and cut the throttle back, the engine would quit.

Can anyone tell me where to look? What could cause this unusual failure. This is about it's 15th flight or so and we never had that problem before.

Thanks!

Tim

How long were you at idle when the engine died? Could be low needle is a little rich & loads up after a long idle.

The other option I can think of is you have the idle trim set too low; go for a high idle until after you land.

It died immediately upon throttling back. Had idle set 3/4 up, sounded a bit too high actually, but was trying to keep it runningg, same thing.

Ok, now I'll show my true Newbie'ness (new word). Is rich clockwise, or counter clockwise, vs. lean on an OS .46 FX?

Thanks!

Rich = COUNTER clockwise (left)
Lean= Clockwise
\
This is for the High Speed (HS) needle!
The Low Speed (LS) screw can go either way depending on if it is an air bleed or not (not sure about the OS; can anyone else help him out?)


Try the following link for EXCELLENT advise on tuning a 2 stroke engine (lotsa other goodies on this site, too):

www.jettengineering.com

--look under "Tech Specs & Instructions"

FX is a two needle carb. Needle in to lean, out to richen, just like hi speed needle.

You say engine runs fine at full throttle, only get problem when you throttle back? After flying? Could be hole in fuel line in tank, try and run engine on deck for ten minutes or whatever your usual flight is, and see if problem occurs.

Andy

...COULD be a ton of different things; I just figured make sure the mixtures were set right first. ;-)

Well, let me add that the fuel tank is completely full, and only flown for a few minutes (enough to go around the pattern once or twice, then land, so, at worst, the tank has been between 3/4 to full for each of these flights.

Tim

A few suggestions,

I had a similar problem with poor idle in flight, almost the same symptoms (high idle setting, ok on ground with full tank). I was running 10% fuel with 20% oil and just a little rich on the high end.

Poor idle could be related to plug problems, don't forget to check your plug. Though this wasn't my problem.

My problem ended up being the fuel I was using. When the jug got down to about 1/3 full I started having these troubles. I swapped out to a new jug of 10% fuel and all my idle problems went away pretty much instantly.

Basically, if you've tuned the carb to death, its time to look at the other little things.

Duke

You have to first eliminate things slowly. Get a fresh plug and then tune the engine up properly. Check the low end settings and the high end settings ... as usual do the pinch test for both settings, I am sure you can get a lot of websites telling you how to do the pinch test.

DO NOT test for maximum RPM on the ground only. Hold the plane at 65 degree or almost vertical and then do the high end tuning. Take it up to full throttle and then RICHEN the HS needle till the RPM drops, then LEAN the HS needle till the engine hits max revs and then start to loose RPM. Once you know where the max is then RICHEN the engine out about say ... 5 clicks.

That is only your almost perfect setting. You will have to fly the plane to see how she handles as the prop loads up. Pull some gradual loops on full throttle to see how the engine performs, if you notice that the engine looses power near the top of the loop then RICHEN the low end a bit.

One thing I noticed about and engine ... I may be wrong but this is something I observed. When you RICHEN the low end, you can then LEAN out the high end more and get more RPM. Anyone else noticed this, of course you need a tach to test this out.

Dukester, that's an interesting observation, as I was down to the last few quarts of a gallon jug of 15% fuel when this occured. Perhaps that's the culprit!

Tim

....How many "last few quarts" are there in a GALLLON of fuel...???!!!!??

[sm=lol.gif]

Ok, ok, TNRabbit, you make a good point. What I meant, I guess, is tank fulls!