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Intermittent 912 ULS problem

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skyring

Joined: 01 Nov 2006
Posts: 32

Posted: Sun Mar 25, 2007 10:52 pm Post subject: Intermittent 912 ULS problem

We now have about 10 hours on the new 912 ULS in the S5 Kitfox. 

Intermittently it will not reach full power, beginning to run rough at about 

4,400 revs and not going over 5 thousand. Seems to occur mainly when the 

engine is getting towards the upper limit of temperature during ground 

running but has also occured during normal temperature in flight.



It will run normally delivering full power and then, after 15 minutes or so 

this problem arises and then disappears again. A little unsettling. Because 

it was intermittent we suspected spark but have changed ignition boxes, 

cables, plugs and it remains. We are beginning to suspect carburettors and 

perhaps mixture at this particular rev. range. Does anyone have similar 

experience that might help us eliminate this? Thanks in advance.



Kerry,

Kitfox builders helper.



 	  Quote: 	
		  




	


_________________________________________________________________

Fox5flyer
Guest

Posted: Mon Mar 26, 2007 4:08 am Post subject: Intermittent 912 ULS problem

It does sound to me like a fuel problem Kerry -- sort of like starvation.

Are you using the milspec 6006 fuel lines?  Then there's all the usual

things like fuel filter, screen, etc.  Ignition problems generally are not

intermittent, IMO.

Good luck and let us know what the problem was when you find it.

Deke



---

jdmcbean(at)cableone.net
Guest

Posted: Mon Mar 26, 2007 10:05 am Post subject: Intermittent 912 ULS problem

Kerry,

	Check the fuel pump...



Fly Safe !!

John & Debra McBean

208.337.5111

www.kitfoxaircraft.com

"It's not how Fast... It's how Fun!"



--

smokey_bear_40220(at)yaho
Guest

Posted: Mon Mar 26, 2007 11:27 am Post subject: Intermittent 912 ULS problem

What about vapor lock?  All fuel system parts FWD of

the firewall should be protected from heat.  Is

anything near the exhaust?  You could be boiling the

fuel.



Kurt S.



--- jdmcbean <jdmcbean(at)cableone.net> wrote:



 	  Quote: 	
		   Kerry,

 	Check the fuel pump...

 

 Fly Safe !!

 John & Debra McBean


	


[quote] --

FLIER(at)sbcglobal.net
Guest

Posted: Mon Mar 26, 2007 12:09 pm Post subject: Intermittent 912 ULS problem

Not sure the age of the engine but check the 

mechanical fuel pump.  



--- Original Message ---

From: kurt schrader <smokey_bear_40220(at)yahoo.com>

To: kitfox-list(at)matronics.com

Subject: RE: Intermittent 912 ULS problem



 	  Quote: 	
		  

<smokey_bear_40220(at)yahoo.com>
	


[quote]

What about vapor lock?  All fuel system parts FWD of

the firewall should be protected from heat.  Is

anything near the exhaust?  You could be boiling the

fuel.



Kurt S.



--- jdmcbean <jdmcbean(at)cableone.net> wrote:



> Kerry,

> 	Check the fuel pump...

> 

> Fly Safe !!

> John & Debra McBean



> --

rjdaugh

Joined: 30 Aug 2006
Posts: 195

Posted: Mon Mar 26, 2007 7:03 pm Post subject: Intermittent 912 ULS problem

Kerry, are the Chokes closing?  Make sure that they are not sticking open.

I had to take mine apart and clean them up and dump the first tanks of fuel.

No problems since.



Randy



.           

--

_________________
Randy
Kitfox 5/7 912S
Black Hills, South Dakota

skyring

Joined: 01 Nov 2006
Posts: 32

Posted: Tue Mar 27, 2007 3:28 am Post subject: Intermittent 912 ULS problem

Thanks to everyone who has responded and sorry I am a bit slow getting back. 

We changed the fuel pump to the new recommended model on the weekend and 

experienced the problem again shortly afterwards. Hoses are all brand new 

and mill spec. In fact everything firewall forward is new and by the Kitfox 

S5 installation book.



We also have a facet pump and filter. Have not yet tried taking that out of 

the equation.



What i did not mention initially was that when the problem occurs, pulling 

on some choke leads to a slight increase in rpm. About 100 I think. Would 

this be normal?



Randy, were your chokes (carbys) new and needed cleaning from new?



Kerry.



 	  Quote: 	
		  

Kerry, are the Chokes closing?  Make sure that they are not sticking open.

I had to take mine apart and clean them up and dump the first tanks of 

fuel.

No problems since.



Randy



.

>

We now have about 10 hours on the new 912 ULS in the S5 Kitfox.

Intermittently it will not reach full power, beginning to run rough at 

about



4,400 revs and not going over 5 thousand. Seems to occur mainly when the

engine is getting towards the upper limit of temperature during ground

running but has also occured during normal temperature in flight.



It will run normally delivering full power and then, after 15 minutes or so

this problem arises and then disappears again. A little unsettling. Because

it was intermittent we suspected spark but have changed ignition boxes,

cables, plugs and it remains. We are beginning to suspect carburettors and

perhaps mixture at this particular rev. range. Does anyone have similar

experience that might help us eliminate this? Thanks in advance.



Kerry,

Kitfox builders helper.



 >

 >

 >

 >



_________________________________________________________________




	


_________________________________________________________________

Express yourself instantly with MSN Messenger! Download today it's FREE!

Fox5flyer
Guest

Posted: Tue Mar 27, 2007 5:05 am Post subject: Intermittent 912 ULS problem

Kerry, the reason I asked about the milspec hose is that they have had a

long history of causing problems.  Although there are no visible external

clues, auto fuel additives tend to cause them to quickly deteriorate and

swell shut on the inside thereby inhibiting fuel flow.  I don't know how

long you have been using them, nor if this is the cause of your problem, but

it sounds familiar and worth considering.  If you use auto fuel, I'd suggest

replacing them anyway with non-milspec fuel line.

Pulling slightly on the enrichener cables (choke) and getting increased rpm

is IMO confirmation that you are having fuel starvation problems.  Careful

analysis and elimination of potentials will soon take care of your problem.

My recommendation is to make one change at a time, test fly, then make the

next one.  Otherwise you won't be sure what the actual problem was.

Good luck.

Deke



 	  Quote: 	
		   

<kerryskyring(at)hotmail.com>
	


 	  Quote: 	
		  

 Thanks to everyone who has responded and sorry I am a bit slow getting

back.
	


 	  Quote: 	
		   We changed the fuel pump to the new recommended model on the weekend and

 experienced the problem again shortly afterwards. Hoses are all brand new

 and mill spec. In fact everything firewall forward is new and by the

Kitfox
	


 	  Quote: 	
		   S5 installation book.



 We also have a facet pump and filter. Have not yet tried taking that out

of
	


 	  Quote: 	
		   the equation.



 What i did not mention initially was that when the problem occurs, pulling

 on some choke leads to a slight increase in rpm. About 100 I think. Would

 this be normal?



 Randy, were your chokes (carbys) new and needed cleaning from new?



 Kerry.



 >

 >Kerry, are the Chokes closing?  Make sure that they are not sticking

open.
	


 	  Quote: 	
		   >I had to take mine apart and clean them up and dump the first tanks of

 >fuel.

 >No problems since.

 >

 >Randy

 >

 >.

 >>

 >We now have about 10 hours on the new 912 ULS in the S5 Kitfox.

 >Intermittently it will not reach full power, beginning to run rough at

 >about

 >

 >4,400 revs and not going over 5 thousand. Seems to occur mainly when the

 >engine is getting towards the upper limit of temperature during ground

 >running but has also occured during normal temperature in flight.

 >

 >It will run normally delivering full power and then, after 15 minutes or

so
	


 	  Quote: 	
		   >this problem arises and then disappears again. A little unsettling.

Because
	


 	  Quote: 	
		   >it was intermittent we suspected spark but have changed ignition boxes,

 >cables, plugs and it remains. We are beginning to suspect carburettors

and
	


 	  Quote: 	
		   >perhaps mixture at this particular rev. range. Does anyone have similar

 >experience that might help us eliminate this? Thanks in advance.

 >

 >Kerry,

 >Kitfox builders helper.

 >

 > >

 > >

 > >

 > >

 >

 >_________________________________________________________________

 >

 >

 >

 >

 >

 >

 >

 >

 >



 _________________________________________________________________

 Express yourself instantly with MSN Messenger! Download today it's FREE!

rjdaugh

Joined: 30 Aug 2006
Posts: 195

Posted: Tue Mar 27, 2007 7:30 am Post subject: Intermittent 912 ULS problem

Kerry, 

Yes they were new.  They were dirtied up by some junk (polystyrene?) left in

the tanks and dissolved out by the first bit of gas in the tanks.  Then as

the gas evaporated in the carbs, it left the junk behind.  I had washed the

tanks carefully with water and soap, but should have done one wash with

acetone.



If you can move the "choke" easily by hand, that is not your problem.  Make

sure they work smoothly by cable.  Mine did initially, but after about an

hour run time, it took a lot of force to get them to move at all.  With some

help from the list, I took them apart, cleaned some ugly yellow "varnish"

off of them with MEK, dumped my tanks, replaced the fuel filters and no more

problems.



Randy



.           

--

_________________
Randy
Kitfox 5/7 912S
Black Hills, South Dakota

Fox5flyer
Guest

Posted: Tue Mar 27, 2007 8:03 am Post subject: Intermittent 912 ULS problem

I felt I should add to this post that what I wrote below is not absolute

because what I'm passing on is information that has been exchanged many

times on this list over the years about Milspec hose.  I don't know if there

has been any scientific data to support what I've posted below, but I have

heard enough reports of it that I tend to believe there is some merit to not

using the Milspec if one plans to use auto gas extensively.

Deke

FWIW

---

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Mar 27, 2007 11:49 am Post subject: Intermittent 912 ULS problem

I might be way off base here.  The problem may not be a fuel problem but one

of too much air getting to the intake side of the engine.  Have a look at

the carburettor boots.  Tug up and down on them to make sure they aren't

either loose or cracked.



Do you have EGT gauges?  Does the EGT rise when you are having the problem?

It could also rise and then sharply fall.



How do the plugs look?  Check them as soon after a flight as possible with

as little operation post problem as possible.  If the plugs show a white

powdery contamination then the engine has been operating too lean.



Noel



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

clint_bazzill(at)hotmail.
Guest

Posted: Tue Mar 27, 2007 3:22 pm Post subject: Intermittent 912 ULS problem

I am going to give my 2 cents worth here.  Everyone else has.  First, I 

think that my engine has more time on it then most other Fox'es.  Over 800 

on this engine 912ULS.  When I first installed my 912ULS, it started up very 

nicely, ran for a few minutes, loaded up and quit.  Removed the fuel bowls 

and drained .  Restarted the engine, same problem.  Called Lockwood and they 

thought it might be over pressure on the float valves.  Before I ordered a 

new one, borrowed my old fuel pump from 912UL.  Same problem,  Called one 

other person that had a 912ULS, he said he had this problem and after an 

hour or so said the problem went away.  Great.  Thought about it for a while 

and concluded, maybe vibration problem, I did have side springs on carb.  

Removed them and the problem went away.  Spent a lot of time running up 

engine etc at airport testing, checking etc.  Flew to Tracy, California.  I 

went to start the engine and it kicked the carbs off.  Couldn't seem to keep 

them on.  Brought trailer to airport and transported it home, 75 miles.  I 

put the carb springs back on, cleaned the boots very well and tested.  It 

ran perfect, that is when I developed the starting technique that I put on 

the list.  My engine has run perfect for over 800 hours.



My advise would be, keep the electric pump turned off.  To have a system 

that would help if mechanical pump failed is too complex to be effecent.  If 

the Rotax pump failed, and you turned on your electric pump you would fill 

your crankcase with fuel, if you had it plumbed with seperate fuel feed, 

would be very very complex.



I would suspect a piece of dirt or something like that in the carb.  The 

engine is designed to act as 2 seperate engines, each run by seperate carb.  

Remove the carbs and check jets very carefully.  Mil 6000 fuel line, I don't 

think is a problem and   If anyone has some new they don't know what to do 

with, will take it.



Good luck.  Clint



(Hope you don't need luck)



From: "Noel Loveys" <noelloveys(at)yahoo.ca>

Reply-To: kitfox-list(at)matronics.com

To: <kitfox-list(at)matronics.com>

Subject: RE: Intermittent 912 ULS problem

Date: Tue, 27 Mar 2007 17:18:50 -0230






I might be way off base here.  The problem may not be a fuel problem but one

of too much air getting to the intake side of the engine.  Have a look at

the carburettor boots.  Tug up and down on them to make sure they aren't

either loose or cracked.



Do you have EGT gauges?  Does the EGT rise when you are having the problem?

It could also rise and then sharply fall.



How do the plugs look?  Check them as soon after a flight as possible with

as little operation post problem as possible.  If the plugs show a white

powdery contamination then the engine has been operating too lean.



Noel



 > --

skyring

Joined: 01 Nov 2006
Posts: 32

Posted: Wed Mar 28, 2007 10:41 am Post subject: Re: Intermittent 912 ULS problem

Thanks so much to everyone. I think we may have it nailed down and I think it is a no-brainer i.e. I have no brains. Reading the comments on fuel starvation got me thinking. The problem usually arises after 15 or 20 minutes of running. We were linking it to the heating up over this time but of course this is about the time it takes to empty the header tank! As soon as this light bulb went off in my head I sent a message to the airfield to check the header tank. Back came a message saying the problem had arisen again, in the air this time, and after about 20 minutes of flight and as it did the low fuel warning light came on. It seems to confirm it's the flow from the wing tanks to the header tank and I think it is as simple as: The fuel lines having a slight bow up as they come out of the tanks. I know, the warnings about this are everywhere! In my defence, I did stress this to the owner and we did make sure they were going downwards but in our concern about folding the wings (we've had to do a lot of it) we left quite a bit of length and it is my guess that during many folding and unfoldings of the wings the hoses have moved up a bit in the clamps and are now slightly bowed up. I'm not at the airfield and can't check this. I am tied to work and fly out of the country for several days tomorrow so will not know until next week. If it is not this then I think it will be something else related to fuel flow from the wing tanks. I think we are on to it. I will advise next week in a new thread. Again thanks. All the replies have been very helpful. 

Kerry. 

PS plane now has 36 minutes flight time. I get to fly it after the 40 hour test period so you can see why I want to get this problem solved.

jdmcbean(at)cableone.net
Guest

Posted: Wed Mar 28, 2007 1:28 pm Post subject: Intermittent 912 ULS problem

Something else to check... It has happened that while pushing the hose onto

the barbed fitting.. the fitting sliced into the hose and created a flap

inside the hose...



Fly Safe !!

John & Debra McBean

208.337.5111

www.kitfoxaircraft.com

"It's not how Fast... It's how Fun!"



--

smokey_bear_40220(at)yaho
Guest

Posted: Wed Mar 28, 2007 4:35 pm Post subject: Intermittent 912 ULS problem

That simple low fuel light can save your bacon as well

as simplify resolving problems.  Highly recommended!



Kurt S.



Do not archive



--- skyring <kerryskyring(at)hotmail.com> wrote:

 

 	  Quote: 	
		   Thanks so much to everyone. I think we may have it

 nailed down and I think it is a no-brainer i.e. I

 have no brains. Reading the comments on fuel

 starvation got me thinking. The problem usually

 arises after 15 or 20 minutes of running. We were

 linking it to the heating up over this time but of

 course this is about the time it takes to empty the

 header tank! As soon as this light bulb went off in

 my head I sent a message to the airfield to check

 the header tank. Back came a message saying the

 problem had arisen again, in the air this time, and

 after about 20 minutes of flight and as it did the

 low fuel warning light came on..........


	




 

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