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Kolb/Jabiru carb overflow
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Frankd

Joined: 28 Mar 2008
Posts: 64

Posted: Sat Jan 08, 2011 8:29 pm Post subject: Kolb/Jabiru carb overflow

Hi guys, 

looking for suggestions here about the 94/40 Bing Carb on the Jabiru 2200 engine. 



I have started my engine but am getting fuel overflow at idle.  I switched out the float needle valve as recommended with the black tipped one and cleaned out everything I could around the needle valve area. 



It still overflows at idle.  

Any ideas on how to fix this and what the issue may be?



My thoughts are:-  a/ the floats are getting stuck somehow in the bowl.

b/ The needle valve seat still has some microscopic fibers or something I can't see.

c/ There is a blockage of vents causing an air pocket and the floats are not fully lifting (one would think the overflow vent would stop this) 



Any ideas and suggestions for a fix are welcome

Thanks

Frankd



M3X

rickofudall

Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

Posted: Sat Jan 08, 2011 9:21 pm Post subject: Kolb/Jabiru carb overflow

Frank, have you checked to make sure the float arm is parallel to the base of the carburetor body when the needle valve is seated? If it is past parallel, i.e. the ends of the arms are closer to the body than the pivot the fuel level will be too high and let fuel overflow. Have you checked the fuel pressure? 

Are you running a boost pump? Is it the correct model that limits fuel pressure to less than 4 psi? Assuming you have a boost pump, remove the float bowl and see if you can shut off the fuel flow by pushing lightly on the needle, then try the same by pushing on the float arms you could have something keeping the float arms from swinging freely.

 I looked at the picture of the pink tipped needle that you posted and it appears by the marks on it that it is seated properly, but all it takes is one imperfection to make it leak. Get a magnifying glass and look the brass seat over carefully. If in doubt replace it.

 



Rick Girard



On Sat, Jan 8, 2011 at 10:29 PM, Frankd <frankd(at)foundrynet.com (frankd(at)foundrynet.com)> wrote:

 	  Quote: 	
		   --> Kolb-List message posted by: "Frankd" <frankd(at)foundrynet.com (frankd(at)foundrynet.com)>

 

 Hi guys,

 looking for suggestions here about the 94/40 Bing Carb on the Jabiru 2200 engine.

 

 I have started my engine but am getting fuel overflow at idle.  I switched out the float needle valve as recommended with the black 	
 

 	  Quote: 	
		   tipped one and cleaned out everything I could around the needle valve area.

 

 It still overflows at idle.

 Any ideas on how to fix this and what the issue may be?

 

 My thoughts are:-  a/ the floats are getting stuck somehow in the bowl.

 b/ The needle valve seat still has some microscopic fibers or something I can't see.

 c/ There is a blockage of vents causing an air pocket and the floats are not fully lifting (one would think the overflow vent would stop this)

 

 Any ideas and suggestions for a fix are welcome

 Thanks

 Frankd

 

 M3X

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=326078#326078

 

 

 

 

 

 

 

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-- 

Zulu Delta

Kolb Mk IIIC

582 Gray head

4.00 C gearbox

3 blade WD

Thanks, Homer GBYM

It is not bigotry to be certain we are right; but it is bigotry to be unable to imagine how we might possibly have gone wrong.

  - G.K. Chesterton



 



  [quote][b]

_________________
The smallest miracle right in front of you is enough to make you happy....

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Sun Jan 09, 2011 5:33 am Post subject: Re: Kolb/Jabiru carb overflow

Rick's recommendations are good ones and hitting on the most probable causes. However, the Jabiru installation manual states that the acceptable maximum fuel pressure is only 3 psi.



From Jabiru Installation manual:



4.4 Pressure to Carburettor (above ambient)

â€¢ Maximum 20 kPa (3 psi)

â€¢ Minimum 5 kPa (0.75 psi)



and



11.3 Mechanical Fuel Pump

The mechanical fuel pump is mounted on the engine crankcase and is camshaft driven. It is

designed to supply fuel at the pressure described in the following paragraph. If fitted, the

electrical boost pump must also fulfill the fuel input criteria for the carburettor, given below.



11.4 Carburettor

A Bing constant depression type 94/40 is used. This carburettor has a minimum delivery

pressure of 5 kPa (0.75 Psi) and a maximum pressure of 20 kPa (3 psi). To confirm that the

fuel system is capable of delivering this pressure a fuel flow test must be performed.

To check pressure, insert a â€˜Tâ€™ piece between the mechanical pump and the carby.

Test boost pump with engine off, then mechanical fuel pump with engine on, then

combine with electrical boost pump as well, before first flight.

A method for performing a fuel flow test is available from Jabiru if required. A drip deflector

to deflect overflowing fuel from the exhaust system is supplied as standard equipment on the

engine.

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Sun Jan 09, 2011 6:43 am Post subject: Re: Kolb/Jabiru carb overflow

Fuel venting causes:



1. float arms not adjusted properly. Fuel level to high in the bowl. (number    

    one cause and an easy fix)

2. rough running engine or poor engine mounts causing the engine to shake 

    so the floats can't properly control the level.

3. boost pump in series and running all the time and has too much fuel  

    pressure to the carb. (not always a problem, but needs to be ruled out)

4. carb not mounted straight. Tilted to one side or the other too much.

5. debris around the carb needle and not effectively controlling fuel flow.



Go after number 1 first and make sure your carb is not tilted.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

Dana

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

Posted: Sun Jan 09, 2011 6:45 am Post subject: Kolb/Jabiru carb overflow

At 12:18 AM 1/9/2011, Richard Girard wrote:

  	  Quote: 	
		  ...but all it takes is one imperfection to make it leak. Get a magnifying glass and look the brass seat over carefully. If in doubt replace it. 	


 How often should one replace the float needle/seat?  Or put another way, how often do they fail?



 Not the same engine or carb, (mine is a Cuyuna with Mikuni carb), but I had what appears to be the same thing, engine flooding while running, after it had been running fine all year.  Happened once before, a few years back, and although the needle/seat didn't look bad then, I replaced it and the problem didn't happen again (until now).  This time it almost put me down in a farm field.  I haven't taken the carb apart yet,but I've ordered a Viton tipped needle (the old one was steel).



 -Dana

 --

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

    [quote][b]

Frankd

Joined: 28 Mar 2008
Posts: 64

Posted: Sun Jan 09, 2011 8:56 am Post subject: Re: Kolb/Jabiru carb overflow

Hi guys,

thanks for the suggestions. 



I do have an electric pump mounted at the bottom level of the tanks and it is a Facet (P/N4015) 4.5Max PSI , but I did not have it on while I get this condition. I now see that Aircraft spruce have a lower PSI pump (!).



I have checked that the carb is not tilting side to side and one thing that came to mind is that it does tilt front to back due to the angle of the whole airframe so I can adjust the floats to close sooner.  The overflow holes are towards the rear of the bowl.



Engine Vibration appears normal, actually quite smooth so this is not a concern.

I will double check the fuel pressure from the mechanical pump if adjusting the floats to close sooner does not work.  I will also test both pumps operating in sequence to see if this causes a problem. 



Replacing the brass insert is on the list if none of the above works. 



Lots to do, thanks again for the pointers.



FrankD



Soon to be fixed M3X

John Hauck

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

Posted: Sun Jan 09, 2011 9:33 am Post subject: Kolb/Jabiru carb overflow

thanks for the suggestions.



 FrankD



 Frank D/Folks:



Correct float bowl level is critical to proper carb operation, as is the 

fuel float bowl static port and the static port in the intake lip of the 

carb.



Float level to high, engine runs rich.  Float level to low, engine runs 

lean.  Set the level per your engine manufacturer's specs.



Correct length and location of the float bowl chamber static port tubing is 

also very important.  The engine manufacturer or Bing should be able to 

provide that information.



That little port and tube are not vents, but static ports.  The front and 

float bowl chamber static ports should read the same static pressure in 

order to operate correctly.



The configuration of the Bing carbs on the 912 series engines, the way they 

are delivered new is the correct set up, per the Rotax folks.  However, I 

discovered that configuration of accessories and location can affect airflow 

and the proper static pressure.  To preclude this I run my float bowl 

chamber static port tube to the inside of my carb air filter covers.  This 

has proven to work well on my airplane.



What works for N101AB, may not work for you.



john h

mkIII

Titus, Alabama - Already up to 30F from a low of 24 last night.  Forecast is 

snow and cold for the next week.  Ugh!!!

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

zeprep251(at)aol.com
Guest

Posted: Sun Jan 09, 2011 2:13 pm Post subject: Kolb/Jabiru carb overflow

Frank,

 I had this issue as well.it would happen occasionally,and I dropped the bowl removed the needle and flushed the seat using the aux pump.It would be OK for a while ,then flood again,even after the new needle.When it happened, I could shut off the fuel run the engine till it leaned out which let the float drop and the needle pull off the seat, then open the fuel valve and it flushed the trash off the needle and seat and it would run fine for a few days.Some microscopic fuzz can do it.

  Starting at the tanks,new paper element filter,new lines all the way through the gascolater,aux pump to the engine driven pump and to the carb, which IS tilted 20 degrees to even up the exhaust temps.No more problems even idle all the time.

 G.Aman MK-3C Jabiru 2200a 600hrs

 

   

 

  

   

 

   

 

  --

ces308

Joined: 03 Nov 2008
Posts: 317
Location: houghton lake ,mi

Posted: Sun Jan 09, 2011 3:00 pm Post subject: Re: Kolb/Jabiru carb overflow

Hi Jabbers..



As you all know I had the problem with the float needle too and after replacing the needle had the same problem...after 3 successful forced landings in 3 weeks,we finally fixed it today...I'm not so sure it was even the float needle to start with...today I got a fuel pressure reading and it was putting out 7 lbs of pressure ! Disconnected the mechanical pump and ran it on the electric pump that was putting out 2-3.2 lbs and it ran perfect ! I removed the mechanical pump,placed an extra .030 gasket between the pump and the engine and the fuel pressure went from 7 lbs to 3.2 and stayed right there and ran great...



Why it started pumping so much more gas I have no idea...



chris ambrose

M3X/jabiru A-2200

N327CS

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Mon Jan 10, 2011 5:57 am Post subject: Re: Kolb/Jabiru carb overflow

Chris,

Very glad to hear you found the actual problem. It IS a mystery as to why it changed over time. 



A couple questions:

1- Had you done any fuel pump maintenance before this happened? What is the total gasket thickness now?

2- Are your electric and mechanical fuel pumps in series or parallel?

3- Do you normally run the electric during all phases of flight?



FWIW, my electric pump is plumbed in parallel with the mechanical and I use the electric to fill the float bowl before starting and during approach and take-off. I know the Facet is a 100% duty cycle pump which could be run full time but it is an old habit of mine not to use it except as stated.



Also, I've never removed my fuel pump so don't know how much gasket is there and I don't have a fuel pressure gage installed so don't know what it is producing. I think I'll ckeck it out during next condition inspection.

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

ces308

Joined: 03 Nov 2008
Posts: 317
Location: houghton lake ,mi

Posted: Mon Jan 10, 2011 12:12 pm Post subject: Re: Kolb/Jabiru carb overflow

Ok...Chapter 14....I thought I had the problem solved ,then I flew it today...stayed over the airport for about 10 minutes  and it seemed to run fine...headed out over the lake,throttled down to loose some altitude and it started all over again...I headed back to the airport and it sounded like it was going to quit again...I kept the throttle wide open and luckily it started to clear out and kept running....land ... Called Pete at Jabiru ,told him about spacing the pump out .030 and it seemed to be ok....his thought now was the spring in the pump needed replacing...I removed the spring...took about 7/16 off the spring put it back on the plane with a fuel pressure Gage and at idle I had 1.7 and it went to almost 3lbs wide open....when I GET THE NEW SPRING ,i WILL PUT IT IN AND TAKE ANOTHER  pressure reading.... 



stay tuned...



chris ambrose

M3X/jabiru

N327CS

ces308

Joined: 03 Nov 2008
Posts: 317
Location: houghton lake ,mi

Posted: Mon Jan 10, 2011 2:15 pm Post subject: Re: Kolb/Jabiru carb overflow

OK..



Our theory   on the spring is this....as the spring gets rusty from condensation it gets more brittle and harder thusly,making more pressure as it pushes the fuel into the carb...cutting it off,making it shorter  also made the spring weaker and reducing the pressure...you think ???When I get the new spring ,I am going to rust proof it just for the heck of it then re-install it and take another pressure reading....



chris ambrose

by0ung(at)brigham.net
Guest

Posted: Mon Jan 10, 2011 2:16 pm Post subject: Kolb/Jabiru carb overflow

Ok...Chapter 14....I thought I had the problem solved ,then I flew it  today...stayed over the airport for about 10 minutes  and it seemed to run  fine...headed out over the lake,throttled down to loose some altitude and it  started all over again...I headed back to the airport and it sounded like it was  going to quit again...I kept the throttle wide open and luckily it started to  clear out and kept running....land ... Called Pete at Jabiru ,told him about  spacing the pump out .030 and it seemed to be ok....his thought now was the  spring in the pump needed replacing...I removed the spring...took about 7/16 off  the spring put it back on the plane with a fuel pressure Gage and at idle I had  1.7 and it went to almost 3lbs wide open....when I GET THE NEW SPRING ,I WILL  PUT IT IN AND TAKE ANOTHER  pressure reading.... 



stay  tuned...



chris ambrose

 >>>>>>>>>>>>>>>

  

 seems that springs loose tension after  time....  I am puzzled on how you would get an increase of  pressure....  is there any chance at a reduced power setting there is a  vibration that is putting enough bubbles in the  float bowl that the float wont sense the correct level?

  

 boyd young

 mkiii

   [quote][b]

rmurrill(at)cox.net
Guest

Posted: Mon Jan 10, 2011 2:55 pm Post subject: Kolb/Jabiru carb overflow

Contrary view...Wow there are thousands of those engines in service, lots with very high hours, and yours is the first to suffer "rusty fuel pump spring hardness"?  I am unaware of the metallurgy that leads to increased elastic modulus from rusted steel surface damage.  Maybe something hangs up on the spring movement or a diaphragm movement......I think I would look again for maybe a vacuum or vent  leak in the induction systems that develops with temperature differential.



Best of luck..



Bob

---- ces308 <ces308(at)ldaco.com> wrote: 

 	  Quote: 	
		   

 

 OK..

 

 Our theory   on the spring is this....as the spring gets rusty from condensation it gets more brittle and harder thusly,making more pressure as it pushes the fuel into the carb...cutting it off,making it shorter  also made the spring weaker and reducing the pressure...you think ???When I get the new spring ,I am going to rust proof it just for the heck of it then re-install it and take another pressure reading....

 

 chris ambrose

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=326355#326355

racerjerry

Joined: 15 Dec 2009
Posts: 202
Location: Deer Park, NY

Posted: Wed Jan 12, 2011 2:52 am Post subject: Re: Kolb/Jabiru carb overflow

All the thoughts expressed here are right on target, but donâ€™t forget the common simple/basic cause of carb flooding which is HEAVY FLOAT.  With metal floats - a leak/pinhole or with composite floats - soggy/porous.

_________________
Jerry King

ces308

Joined: 03 Nov 2008
Posts: 317
Location: houghton lake ,mi

Posted: Wed Jan 12, 2011 5:18 pm Post subject: Re: Kolb/Jabiru carb overflow

Hi Jabbernuts ! 



Did anyone here know there are 2 different springs??  The silver one is the one we are supposed to have ..it puts out 2-3 lbs....the gold spring puts out 7 lbs....and some of the engines "got out" with the gold springs.....Imagine that.....Mine was to rusted to see what color ( seee picture)  even after we cleaned it up...



chris ambrose

M3X/Jabiru

N327cs

ces308

Joined: 03 Nov 2008
Posts: 317
Location: houghton lake ,mi

Posted: Wed Jan 12, 2011 5:21 pm Post subject: Re: Kolb/Jabiru carb overflow

sorry...forgot the pictures...



chris ambrose

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williamtsullivan(at)att.n
Guest

Posted: Wed Jan 12, 2011 5:39 pm Post subject: Kolb/Jabiru carb overflow

Chris- looks like condensation from somewhere.

  

                                            Bill Sullivan

                                            Windsor Locks, Ct.

                                            FS 447



--- On Wed, 1/12/11, ces308 <ces308(at)ldaco.com> wrote:



  	  Quote: 	
		  

From: ces308 <ces308(at)ldaco.com>

Subject: Re: Kolb/Jabiru carb overflow

To: kolb-list(at)matronics.com

Date: Wednesday, January 12, 2011, 8:21 PM



 --> Kolb-List message posted by: "ces308" <ces308(at)ldaco.com (ces308(at)ldaco.com)>



sorry...forgot the pictures...



chris ambrose





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 [quote][b]

rmurrill(at)cox.net
Guest

Posted: Wed Jan 12, 2011 6:09 pm Post subject: Kolb/Jabiru carb overflow

Wow..."got out"....we used to call that an "escapement " in the DoD universe.  Sounds like you are very close to getting back to a highly reliable powerplant!

Do not archive

---- ces308 <ces308(at)ldaco.com> wrote: 

 	  Quote: 	
		   

 

 Hi Jabbernuts ! 

 

 Did anyone here know there are 2 different springs??  The silver one is the one we are supposed to have ..it puts out 2-3 lbs....the gold spring puts out 7 lbs....and some of the engines "got out" with the gold springs.....Imagine that.....Mine was to rusted to see what color ( seee picture)  even after we cleaned it up...

 

 chris ambrose

 M3X/Jabiru

 N327cs

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=326776#326776

ces308

Joined: 03 Nov 2008
Posts: 317
Location: houghton lake ,mi

Posted: Wed Jan 12, 2011 8:42 pm Post subject: Re: Kolb/Jabiru carb overflow

"Wow..."got out"....we used to call that an "escapement " in the DoD universe. Sounds like you are very close to getting back to a highly reliable powerplant! "



    This really has been a very reliable engine and other than this,I could be happier with this engine ! It should be all better next week....then look out  for the new videos !!!  lol



chris ambrose

M3X/jabiru   A-2200

N327CS

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