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Strange fuel related problem ..

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noelbou(at)vif.com
Guest

Posted: Thu Aug 02, 2007 10:57 am Post subject: Strange fuel related problem ..

Hello all,



I am a long time lurker and the owner, since 1999, of a 1990 "vintage"

Twinstar MK II .



I had a strange problem today with my "old faitfull" Rotax 503 with

(single) point ignition ... (yes ...)

I started the engine and then walked away a few feet to talk to a friend

(who just bought a gorgeous MK III with 912s) ...

and suddently the engine started to slow down and then stopped

completely after a few second.

.. as if it would have died from fuel starvation  ... Would not "take"

any throttle input ... while slowing down ...



So i checked and found that both carbs "cups" where almost empty (!)

So ... i suspected a gas pump problem (mikuni) ... did a few checks ...

checked that the gas thanks were vented properly

(yes they were)  and i started again ...



The engine ran roughly probably on 1 cylinder ...  stopped and checked

again and this time

only one of the carb cup was empty and the other one normal (full) ..

Then i removed and checked the part that let the gas in the carb (name

?)  (needle controlled by float level)

for any debris or clogging ... and found nothing ... reassembled

everything and fired up the engine.



This time it ran fine ... ran it a 6000 RPM on the ground for  ~ 1 min

with no problems ...

Stopped it and restarted a few times and did a couple more low and high

RPM run and everything seemed  normal ...

So ... i  took off , did a couple of circuits in the pattern and then

headed for a mechanically uneventfull but beatifull flight in the

beatifull Montreal surroundings ...



Now, i (and my friend, who previously owned this plane an flew it > 200

hrs) are just puzzled as what could have been the cause of this strange

behaviour ... ???

- Obviously not a gas pump problem as it ran fine for 1 1/2 hour after .

- Not a gas tank venting problem ... or gas filter, pump etc (as all ran

fine for the 1 1/2 flight)



So what could have caused this "trange behaviour" ?



Any hint greatly appreciated ...



Noel Bouchard

Montreal, Canada

Twinstar MK II with Rotax 503

380 Hrs



P.S. This Twinstar MK II is another living proof of the quality of the

Kolb aircrafts ... and Rotax 503 engines.

It now has well over 800 hrs. on the frame and engine. ( i am the 3th

owner) The Rotax 503 has had good maintenance and was fully rebuilt

at ~ 700 Hrs. I myself have cumulated some 380 hours of flight on this

MK II and 503 and experienced only

two small engine problems. One related to water contamination in (my

first) winter, and another due to

a mistake in a new point set installation which caused premature wear

and engine problem on 1 cyl.

In both even, the engine did not stop, but ran on one cylinder and

allowed for easy precaution landings ...

So i can say this plane and engine have been very reliable. Now i may be

lucky

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captainron1(at)cox.net
Guest

Posted: Thu Aug 02, 2007 6:44 pm Post subject: Strange fuel related problem ..

I would suspect a Gremlin passing through, or some air in the line. 



Ron (Arizona)

==================================

---- "NoÃ«l Bouchard" <noelbou(at)vif.com> wrote: 



=============




Hello all,



I am a long time lurker and the owner, since 1999, of a 1990 "vintage"

Twinstar MK II .



I had a strange problem today with my "old faitfull" Rotax 503 with

(single) point ignition ... (yes ...)

I started the engine and then walked away a few feet to talk to a friend

(who just bought a gorgeous MK III with 912s) ...

and suddently the engine started to slow down and then stopped

completely after a few second.

.. as if it would have died from fuel starvation  ... Would not "take"

any throttle input ... while slowing down ...



So i checked and found that both carbs "cups" where almost empty (!)

So ... i suspected a gas pump problem (mikuni) ... did a few checks ...

checked that the gas thanks were vented properly

(yes they were)  and i started again ...



The engine ran roughly probably on 1 cylinder ...  stopped and checked

again and this time

only one of the carb cup was empty and the other one normal (full) ..

Then i removed and checked the part that let the gas in the carb (name

?)  (needle controlled by float level)

for any debris or clogging ... and found nothing ... reassembled

everything and fired up the engine.



This time it ran fine ... ran it a 6000 RPM on the ground for  ~ 1 min

with no problems ...

Stopped it and restarted a few times and did a couple more low and high

RPM run and everything seemed  normal ...

So ... i  took off , did a couple of circuits in the pattern and then

headed for a mechanically uneventfull but beatifull flight in the

beatifull Montreal surroundings ...



Now, i (and my friend, who previously owned this plane an flew it > 200

hrs) are just puzzled as what could have been the cause of this strange

behaviour ... ???

- Obviously not a gas pump problem as it ran fine for 1 1/2 hour after .

- Not a gas tank venting problem ... or gas filter, pump etc (as all ran

fine for the 1 1/2 flight)



So what could have caused this "trange behaviour" ?



Any hint greatly appreciated ...



Noel Bouchard

Montreal, Canada

Twinstar MK II with Rotax 503

380 Hrs



P.S. This Twinstar MK II is another living proof of the quality of the

Kolb aircrafts ... and Rotax 503 engines.

It now has well over 800 hrs. on the frame and engine. ( i am the 3th

owner) The Rotax 503 has had good maintenance and was fully rebuilt

at ~ 700 Hrs. I myself have cumulated some 380 hours of flight on this

MK II and 503 and experienced only

two small engine problems. One related to water contamination in (my

first) winter, and another due to

a mistake in a new point set installation which caused premature wear

and engine problem on 1 cyl.

In both even, the engine did not stop, but ran on one cylinder and

allowed for easy precaution landings ...

So i can say this plane and engine have been very reliable. Now i may be

lucky 





--

kugelair.com

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gaman(at)att.net
Guest

Posted: Fri Aug 03, 2007 9:27 am Post subject: Strange fuel related problem ..

it only takes the smallest hair to get caught between the fuel inlet or outlet check valves to interfere with the low speed operation of a diaphragm pump.Do you have a paper element filter between the tank and the pump?



Ron <captainron1(at)cox.net> wrote:[quote] --> Kolb-List message posted by: Ron 



I would suspect a Gremlin passing through, or some air in the line. 



Ron (Arizona)

==================================

---- "Noël Bouchard"  wrote: 



=============

--> Kolb-List message posted by: =?ISO-8859-1?Q?No=EBl_Bouchard?= 



Hello all,



I am a long time lurker and the owner, since 1999, of a 1990 "vintage"

Twinstar MK II .



I had a strange problem today with my "old faitfull" Rotax 503 with

(single) point ignition ... (yes ...)

I  started the engine and then walked away a few feet to talk to a friend

(who just bought a gorgeous MK III with 912s) ...

and suddently the engine started to slow down and then stopped

completely after a few second.

... as if it would have died from fuel starvation  ... Would not "take"

any throttle input ... while slowing down ...



So i checked and found that both carbs "cups" where almost empty (!)

So ... i suspected a gas pump problem (mikuni) ... did a few checks ...

checked that the gas thanks were vented properly

(yes they were)  and i started again ...



The engine ran roughly probably on 1 cylinder ...  stopped and checked

again and this time

only one of the carb cup was empty and the other one normal (full) ..

Then i removed and checked the part that let the gas in the carb (name

?)  (needle controlled by float level)

for any debris or clogging ... and found nothing ... reassembled

everything and fired up the  engine.



This time it ran fine ... ran it a 6000 RPM on the ground for  ~ 1 min

with no problems ...

Stopped it and restarted a few times and did a couple more low and high

RPM run and everything seemed  normal ...

So ... i  took off , did a couple of circuits in the pattern and then

headed for a mechanically uneventfull but beatifull flight in the

beatifull Montreal surroundings ...



Now, i (and my friend, who previously owned this plane an flew it > 200

hrs) are just puzzled as what could have been the cause of this strange

behaviour ... ???

- Obviously not a gas pump problem as it ran fine for 1 1/2 hour after .

- Not a gas tank venting problem ... or gas filter, pump etc (as all ran

fine for the 1 1/2 flight)



So what could have caused this "trange behaviour" ?



Any hint greatly appreciated ...



Noel Bouchard

Montreal, Canada

Twinstar MK II with Rotax 503

380 Hrs



P.S. This Twinstar MK II [quote][b]

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noelbou(at)vif.com
Guest

Posted: Fri Aug 03, 2007 10:06 am Post subject: Strange fuel related problem ..

Hello Ron & Gary & all 



Thanks for your replies ...

The air in the line may be the right answer but ... then why both empty 

.. then one ...

and then both ok ... ?  Some debris in the pump, that maybe affected 

both "sides" and then one and then went away ?



Yes there is a filter in the line and i think it is paper (and the next 

thing to get replaced ...)

I will also order a pump rebuilt kit ... just to be on the safe side ... 

will also give me the

opportunity to inspect it ...



But i am still poundering wether a lost gremlin might have something to 

do with this 



Best ...



Noel



gary aman wrote:



 	  Quote: 	
		   it only takes the smallest hair to get caught between the fuel inlet 

 or outlet check valves to interfere with the low speed operation of a 

 diaphragm pump.Do you have a paper element filter between the tank and 

 the pump?



 Ron <captainron1(at)cox.net> wrote:



     



     I would suspect a Gremlin passing through, or some air in the line.



     Ron (Arizona)

     ==================================

     ---- "Noël Bouchard" wrote:

- The Matronics Kolb-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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