Dies at high idle- help

Start the motor, idles fine for 30 seconds and then dies with no input change. Ideas ? On attempt to restart I couldn't get it started until I tried pumping the throttle all the way in and then pulling it back quickly. Doesn't start easily at all.

Got the cowls off the next day and it fired right up, no problems. - it also passed the 30-60 sec interval with no problems. After hours of sitting again i started it up and was taxing back to the hangar and once again suddenly dies. Guessing around 1000rpm~ once again very hard to start but with some serious pumping and cranking I can get it. After restart I can't replicate it. So something is happening right after a cold start 30-60 seconds in.

Any suggestions or tests welcome

Carb ice? What's temp/humidity in Logan lately?

Yeah it's cold. Is this something that has happened to people ? They have to use carb heat while warming up and taxiing ? Haven't thought of it thanks. Anyone else ?

intake leak makes mixture too lean. carb heat enriches mixture. engine then runs better.

check for intake leak.

good luck.

Also as the temp decreases the mixture gets leaner right ? Cause a few weeks ago it was a non issue

Carbureted

erikpmort said:

Also as the temp decreases the mixture gets leaner right ? Cause a few weeks ago it was a non issue

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I assume this is a carbureted engine since you are pumping the throttle.

It doesn't seem logical that if it was running correctly a couple of weeks ago that a temperature change would cause this. I would suspect a fuel flow problem, intake leak or crud in the carb. How long since the carb has been apart? When it is wanting to quit, did you try the aux fuel pump?

Yes turned on the boost pump and still very hard to start. I agree with induction leak or carb we will go that route and report back thanks

Well today the problem progressed from intermittent to permanent. Cannot start the motor now. Even waiting for a long time like before doesn't matter. I see it as something positive because it will be easier to diagnose now. We have plenty of fuel to the gas collator, tomorrow we will check ignition.

I'm trying to think of something that could have caused this. I did have my first dead battery the other day and had to jump it- could I have caused an over voltage- maybe I should check fuses ? Throwing it out there. Just trying to think what recent event has caused a change

This sounds an awful lot like some of the other intermittent fuel flow blockages we've heard about in other threads. Have you tried disconnecting the fuel line at the carb and turning on the electric pump? What were the results?

Yeah that was the exact test we ran yesterday. But thanks, keep the ideas flowing

erikpmort said:

Yeah that was the exact test we ran yesterday. But thanks, keep the ideas flowing

Click to expand...

OK, it sounded like you checked for flow at the gascolator only, which depending on your fuel system design could be rather far upstream of the carb. Restriction could be further downstream.

Do you have mags, electronic ignition, or a combination?

Fixed.

So I think all of my incident related probems are now solved. A&P went through the carb- my idle was too low 500 rpm when warm and also too lean- no rise when pulling to idle cut off. We have a nice 700 rpm idle now with around 50 rpm rise when pulling to shutdown. Also the same mag that stranded me in George started acting up and we replaced the condenser and contact points. Very pleased with my local mechanic that really made multiple efforts to tweak the idle settings.

As far as that mag goes however this is strike two. Strike three its garbage and I go emag.

Big lesson learned- when you check idle in your preflight runup- you are checking for specific things. Not just that it doesn't die or run rough. I learn more everyday.

Ps loving my almost a 14 mod and ultimate gust lock.

Glad you got it figured out. And thanks for sharing the solution - I definitely learned something from it.

Not fixed.

Spoke too soon. Hadn't flown for a week- started her up and taxied out to the runup- right as I got there the motor sputtered and quit. I saw it coming and pumped the throttle and it wouldn't obey. For some reason you cannot immediately restart it. If you wait a minute and then try, it will come to life if you give full throttle pumps. Once I restart it, it will not do it again ! This is driving me nuts.

As a side note- the mag and idle were original problems- this new problem may or may not have been a contributor to the emergency landing. It's funny that I flew it 3-5 times after the repair before It presented.

As another side note the reiff strip that i just installed is totally awesome. 75cht and over 100 oil temp when I started it today and it fired first blade. You can tell it likes it much better than my 40-50 deg oil temp starts in the past.