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Engine quit today, now to figure out why?

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Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Sun May 11, 2008 1:34 pm Post subject: Engine quit today, now to figure out why?

Strange behavior from my engine today...



Today I decided, for the first time since I've owned it, to fly my 

UltraStar to another airport about 10 miles away.  Previously all my 

flights have been in the close vicinity of my home field.  Anyway, 'bout 

10-15 minutes into the flight, cruising at 5700 rpm and 3000', I lost 

power.  It didn't actually quit; it was more like it was just throttled 

back suddenly.  My hand at the moment wasn't on the throttle but on my lap, 

keeping warm.  Without thinking to check where the throttle was, I reached 

down and pushed it forward, and I instantly had full power again.  Temps 

were normal.



My first thought was that the throttle friction lock had slipped, but to be 

safe I headed back home.  The engine continued to run normally, so I just 

flew around for another 5 minutes or so over the airport, letting the plane 

slowly climb to about 3500', then reduced power to about 3000 rpm to 

descend at cruise airspeed.  After a minute or two of this, the engine 

just... quit.  I wasn't too alarmed as I was right over the airport, so I 

tried to restart.  Several pulls and nothing, then a couple shots of prime, 

and finally it caught and started at full throttle, but with no power.  Too 

much prime, perhaps, as jockeying the throttle a few times brought it back 

to normal power, and I had no further trouble, though I landed as soon as 

possible.



On the ground, the engine ran fine at all throttle settings from idle to 

WOT.  Killed the ignition at 5500 and checked the plugs; I would say they 

were too light except that they were brand new before this flight.  Wiggled 

the wires while running, no hint of trouble there.



This is the ULII-02 engine, low hours, Mikuni carb, jetted (310 main jet) 

per manufacturer's specs for sea level (where my airport is) at 40-60°F 

(temps today were around 60), and the plug color previously indicated the 

specs are appropriate.  Running 93 octane auto gas (switched from 100LL a 

few weeks ago).  The new plugs were the only change since the last flight 

(the old plugs were fine but I wanted to replace them with solid terminal 

plugs).  The only other odd thing was the plugs were slightly too loose 

(when I installed them after the last flight I was using a different wrench 

and didn't tighten them enough), but they weren't _loose_, just not 

properly torqued.  The only other odd thing I noticed (or perhaps not odd, 

just never noticed before) is that in flight (but not on the ground) it 

didn't want to seem to hold exactly 3000 rpm, and the EGT fluctuated a bit 

at that rpm.



At this point I'm a bit nervous... and open to ideas.



-Dana

--

  I no longer need to punish, deceive or compromise myself. Unless, of 

course, I want to stay employed.

DAquaNut(at)aol.com
Guest

Posted: Sun May 11, 2008 1:50 pm Post subject: Engine quit today, now to figure out why?

In a message dated 5/11/2008 4:35:14 P.M. Central Daylight Time,  d-m-hague(at)comcast.net writes:

  	  Quote: 	
		  At this    point I'm a bit nervous... and open to  ideas.



-Dana

-- 	
  

            Were the  EGTS  running high while you were coasting down at 3000 rpm?    Any Ethanol in the gas? Ethanol does cause the engine to run leaner than plain  gas.  Did it load up possibly?   Let us know what you come up  with!  

  

       Ed       FF#62



Wondering what's for Dinner Tonight? Get new twists on family favorites at AOL Food.

  [quote][b]

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Sun May 11, 2008 3:17 pm Post subject: Engine quit today, now to figure out why?

At 05:48 PM 5/11/2008, DAquaNut(at)aol.com wrote:

  	  Quote: 	
		    

            Were the EGTS  running high while you were coasting down at 3000 rpm?   Any Ethanol in the gas? Ethanol does cause the engine to run leaner than plain gas.  Did it load up possibly?   Let us know what you come up with! 	


 I didn't look that I can recall, but I don't think so...  typically the EGT drops right down as soon as I reduce the throttle below cruise.  There _is_ ethanol (probably 10%) in the gas, but the air temp (almost warm enough to use the next smaller jet) and the 3500' altitude makes me thing it would be rich, if anything.  Loading up is a possibility, but it took prime to restart it.



 A poster on another list suggested carb ice, and the temp/dewpoint supports that, but at cruise that would make for a gradual rpm drop, not sudden as I experienced... and the last time I concluded a carb ice problem I was wrong (and these engines / carbs aren't terribly prone to icing anyway).  Also the quick recovery in the first case, and the restart in the second case, make me not think that's it... but I could be wrong.



 -Dana

 --

  Society is like a stew. If you don't keep it stirred up, you get a lot of scum on top.    [quote][b]

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Sun May 11, 2008 3:34 pm Post subject: Engine quit today, now to figure out why?

Dana:

  

 If it were my Cuyuna and US, I would first  ascertain that the throttle lever had enough friction and had not vibrated  towards the closed position.

  

 If throttle position was not the culprit, I'd check  to make sure the engine was not trying to seize.  Two strokes are  sneaky.  They'll set a pilot up to bust his ass later down the road.   I know that from experience.

  

 I would not suspect carb problems.  How would  the carb change unless you changed it?

  

 Ignition is CDI and not adjustable.  A though  though.  Doesn't the Cuyuna CDI work just opposite from the Rotax?   Trying to remember, but one of them must be grounded to run.  I believe it  is the Cuyuna.  If you did not have a good ground, you may have been having  some ignition problems.

  

 I'm brain storming, for what it is worth.   Been a long time since I had a two stroke drive me nuts.  Easy to forget a  lot of stuff.

  

 Had a ULII02 that failed a PTO crank bearing.   Gave very similar symptoms as yours right up until the crank shaft locked  up.

  

 john h

 mkIII

 [quote]    Also the quick recovery in the first case,    and the restart in the second case, make me not think that's it... but I could    be wrong.



-Dana



    

[b]

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Sun May 11, 2008 3:54 pm Post subject: Engine quit today, now to figure out why?

At 07:32 PM 5/11/2008, John Hauck wrote:

  	  Quote: 	
		   

 If it were my Cuyuna and US, I would first ascertain that the throttle lever had enough friction and had not vibrated towards the closed position. 	


 That was my first thought, but it never happened before, and it seemed normal afterwards.  And it definitely wasn't the problem the second time.



  	  Quote: 	
		  I would not suspect carb problems.  How would the carb change unless you changed it? 	


 I don't suspect that either; I only mentioned jetting to paint a full picture.



  	  Quote: 	
		  Doesn't the Cuyuna CDI work just opposite from the Rotax?  Trying to remember, but one of them must be grounded to run.  I believe it is the Cuyuna.  If you did not have a good ground, you may have been having some ignition problems. 	


 Correct, the Cuyuna must be grounded to run.  Ignition problem would explain the second time (when it actually quit), but not the drop in rpm the first time.



  	  Quote: 	
		  Had a ULII02 that failed a PTO crank bearing.  Gave very similar symptoms as yours right up until the crank shaft locked up. 	


 Really?  Intermittent failure and easy restart?  How would you check it?  Come to think of it, there _was_ a funny sound as I climbed out on my first takeoff, but it went away after I throttled back to cruise power.  I landed anyway, found nothing wrong, but some of the prop leading edge tape was loose so I trimmed it back... and I didn't hear the noise after that, so I took off again.  It was a light sound, like something fluttering in the wind, or a loose muffler spring (it wasn't but I'm trying to describe it), or perhaps even ignition noise in my headset.



 -Dana

 --

  If email had been around before the telephone was invented, people would have said, "Hey, forget email! With this new telephone invention I can actually talk to people!"    [quote][b]

The BaronVonEvil

Joined: 23 Jun 2006
Posts: 76
Location: Walla Walla, WA.

Posted: Sun May 11, 2008 5:08 pm Post subject: Re: Engine quit today, now to figure out why?

Hi Dana,



You might want to check the fuel filters for dirt.  Also check your fuel tank pickups and the inside of the tanks themselves. Pull the carburetor bowl and check it for dirt as well. 



Dirt may be choking off the fuel flow as fuel is being pulled to the engine by the fuel pump.  Dirt will sometime collect at the pickups as fuel is flowing and drift away from the pickups once the fuel flow has ceased.



You should also do a compression check of the engine to help verify it is okay.  A small LED light  through the spark hole can be used to inspect the condition of the cylinder walls with the pistons at bottom dead center.



It sounds like a fuel starvation issue to me. Usually when an ignition system quits it stays dead until the cause is remedied.



Just My Two Cents,



Carlos G

Ralph B

Joined: 14 Apr 2007
Posts: 367
Location: Mound Minnesota

Posted: Sun May 11, 2008 5:11 pm Post subject: Re: Engine quit today, now to figure out why?

Dana, you can take the exhaust manifold off and check the rings and cylinders. Look for any scuffing and stuck rings. The engine can run on one piston ring, but it will lack power.



If you don't find anything, run it for a full 10 minutes tied on the ground. An easy way to do this is with an auto tow rope. Wrap one end around the front wheel of your car and the ground, and the other end wrapped around the tailwheel assembly.



Ralph

_________________
Ralph B

Kolb Kolbra 912uls
N20386
550 hours

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Sun May 11, 2008 6:44 pm Post subject: Engine quit today, now to figure out why?

At 09:11 PM 5/11/2008, Ralph B wrote:



 	  Quote: 	
		  Dana, you can take the exhaust manifold off and check the rings and 

cylinders. Look for any scuffing and stuck rings. The engine can run on 

one piston ring, but it will lack power.


	


Didn't have partial power, it just quit... then restarted and run at full 

power.  But it is something to check if I don't find anything else.



 	  Quote: 	
		  If you don't find anything, run it for a full 10 minutes tied on the 

ground. An easy way to do this with an auto tow rope. Wrap one end around 

the front wheel of your car and the ground, and the other end wrapped 

around the tailwheel assembly.


	


Ran it afterwards for several minutes at WOT (chocks alone will hold 

it).  No problems in that time.



-Dana

--

  "Very funny, Scotty.  Now beam down my clothes."

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Sun May 11, 2008 6:50 pm Post subject: Engine quit today, now to figure out why?

At 09:08 PM 5/11/2008, The BaronVonEvil wrote:



 	  Quote: 	
		  You might want to check the fuel filters for dirt.  Also check your fuel 

tank pickups and the inside of the tanks themselves. Pull the carburetor 

bowl and check it for dirt as well.


	


The filter (clear glass) is clean, but I'll check the bowl.



 	  Quote: 	
		  Dirt may be choking off the fuel flow as fuel is being pulled to the 

engine by the fuel pump.  Dirt will sometime collect at the pickups as 

fuel is flowing and drift away from the pickups once the fuel flow has ceased.


	


Possible but doubtful, as I have two interconnected tanks, and two 

independent pickups tee'd together feeding the engine.



 	  Quote: 	
		  You should also do a compression check of the engine to help verify it is 

okay.  A small LED light  through the spark hole can be used to inspect 

the condition of the cylinder walls with the pistons at bottom dead center.



It sounds like a fuel starvation issue to me. Usually when an ignition 

system quits it stays dead until the cause is remedied.


	


A major mechanical engine problem doesn't seem to fit the symptoms.  A fuel 

problem seems more likely... the fuel pump is another thing I need to look at.



-Dana

--

  "Very funny, Scotty.  Now beam down my clothes."

Dwight

Joined: 21 Feb 2008
Posts: 12
Location: Illinois

Posted: Sun May 11, 2008 8:31 pm Post subject: Re: Engine quit today, now to figure out why?

[quote="The BaronVonEvil"]Hi Dana,



You might want to check the fuel filters for dirt.  Also check your fuel tank pickups and the inside of the tanks themselves. Pull the carburetor bowl and check it for dirt as well. 



Dirt may be choking off the fuel flow as fuel is being pulled to the engine by the fuel pump. >>



agreed-

I would consider pulling the 90's and tee's off of your fuel system and examining them real close.  I've seen the metal 90's that push in the grommet plug up really bad from rust and crud.  Same goes for the tees.

I've also seen a old grommet break a pc off and this lodge in the fitting.  If you have an old fuel system, and have recently started using ethanol this can start stuff breaking loose and plugging fittings etc.  You might also consider the fuel pump if it is getting old.



Just my .02  hope you get it figured out soon.



Dwight

Dave Rains

Joined: 24 Apr 2007
Posts: 47

Posted: Mon May 12, 2008 6:03 am Post subject: Re: Engine quit today, now to figure out why?

 	  Ralph B wrote: 	
		  Dana, you can take the exhaust manifold off and check the rings and cylinders. Look for any scuffing and stuck rings. The engine can run on one piston ring, but it will lack power.



If you don't find anything, run it for a full 10 minutes tied on the ground. An easy way to do this is with an auto tow rope. Wrap one end around the front wheel of your car and the ground, and the other end wrapped around the tailwheel assembly.



Ralph 	




I agree with this recommendation.  Had the same symptoms with a Rotax.  The engine was seizing, and as soon as it cooled down for a few seconds would start again.  I would certainly make sure you pull the manifold and look inside.

Dave

_________________
Dave Rains
N8086T

jb92563

Joined: 23 Mar 2007
Posts: 314
Location: Southern California

Posted: Tue May 13, 2008 6:37 am Post subject: Re: Engine quit today, now to figure out why?

I ran my UL-202 this past weekend, and tried without the fuel pump to see what would happen and found the engine does not suck fuel well at all on its own.



Might be worth while to check your pump.



I replaced my pump diaphrams/gaskets $4 just for good measure.



Also if your fuel line is thin it could suck the walls shut temporarily blocking fuel flow....not likely but if the fuel line is old you never know.



Fuel line air leaks are also insideous....I discovered one due to the clamp chewing into the Tygon fuel line....replaced the clamp with a zip tie.

It did not leak fuel but when I pulled on it a bit the hole opened and a fine spritze of fuel came out.

It really does sound like fuel starvation.



I think I'll consider an overhead starter like yours seeing as how it demonstratably worked for you in flight.

_________________
Ray

Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider

Do Not Archive

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Wed May 14, 2008 5:34 pm Post subject: Engine quit today, now to figure out why?

At 10:37 AM 5/13/2008, jb92563 wrote:



 	  Quote: 	
		  I ran my UL-202 this past weekend, and tried without the fuel pump to see 

what would happen and found the engine does not suck fuel well at all on 

its own.


	


No, it would not.



 	  Quote: 	
		  It really does sound like fuel starvation.


	


Now, I'm less sure.  Yesterday before trailering the plane home, I pulled 

it out to look at things.  I noticed fuel dribbling from the carburetor 

vent tubes, something I've never noticed before.  And the trailer floor 

under the carb was damp with fuel/oil.  This is a pretty clear indication 

of a leaky float needle, which would cause _rich_ running, not fuel 

starvation.  Still, an excessively rich mixture can also cause engine 

stoppage... or a worn needle could also stick closed.  Or crud, but either 

way it's pointing to a carburetor issue... probably won't pull it apart 

until the repair parts arrive in a few days, though.



 	  Quote: 	
		  I think I'll consider an overhead starter like yours seeing as how it 

demonstratably worked for you in flight.


	


Yes, it sure was nice to have!  It makes for a better pull angle on the 

ground, too.  It's just a piece of stainless sheet bent into a "U" shape 

holding a pulley, on the LH universal joint bolt.



-Dana



--

  Q: Why is it that New Jersey got all the toxic waste dumps and California 

got all the lawyers?

A: New Jersey had first choice.

jb92563

Joined: 23 Mar 2007
Posts: 314
Location: Southern California

Posted: Wed May 14, 2008 10:26 pm Post subject: Re: Engine quit today, now to figure out why?

Thats puzzling as it took prime to restart in the air.



I wonder if the floats could be binding causing the possibility of lean or rich.



I found acetone dissolves the gunk very quickly.



I have my Cuyuna 430 mounted tonight on the US and am soaking the carb in acetone to get rid of all the old gunk.



I'll let it soak overnight and tomorrow evening brush and flush it out and mount it on the engine.



Should be able to try out the engine this weekend.

_________________
Ray

Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider

Do Not Archive

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Thu May 15, 2008 2:28 am Post subject: Engine quit today, now to figure out why?

At 02:26 AM 5/15/2008, jb92563 wrote:



 	  Quote: 	
		  Thats puzzling as it took prime to restart in the air.



I wonder if the floats could be binding causing the possibility of lean or 

rich...


	


That's a possibility.  Another possibility is that it died rich, wouldn't 

start at low throttle first, but then when I opened the throttle, there was 

then too little fuel in the intake for it to start at WOT, until I primed 

it?  I dunno, just guessing now until I can take it apart, probably not 

'til next week.



-Dana



--

  Dyslexics Untie!

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