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SC 52 2-Stroke keeps cutting out.

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Ben Kelly11/05/2008 18:21:00
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The problem i have is the SC 52 that is installed in my Seagull edge 540. It likes to cut out when the fuel tank is about half empty, now originally i noticed the needle valve was leaning itself out and i have fixed that, then i thought it was overheating so i flew it without the cowl and this problem still persists.

I have checked the Clunk in the fuel tank and it is not trapped or restricted in any way.

 I just cant figure out what the problem is.

Any help will be appreciated.

Cheers. 

Tim Mackey11/05/2008 18:46:00
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pinhole in the clunk line inside the tank ? Not affecting the situ when tank is full, but as level drops, and hole is exposed, air bleeds in  - change the lines for good measure, and besides, it eliminates one potential problem.
Nobby Clarke 211/05/2008 21:01:00
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 That's exactly what I would look for,pin hole in the fuel line .

Tim Mackey11/05/2008 21:49:00
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Well I am glad you agree Nobby, but looking for it will probably be fruitless - he could try sealing the end and blowing through it into water or oil etc, and watch for tiny bubbles...but frankly I would just change it full stop.
Ben Kelly11/05/2008 22:33:00
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Ohh ye i never thought of that, i checked all the fuel line from the tank to the engine, but it never dawned on me that the fuel line inside the tank can get damaged aswell.

Well i'll check that and if its not then you will be hearing from me again haha.

Tim Mackey11/05/2008 22:37:00
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They often break where they join the brass tube inside the tank - whilst its all out and being changed, ensure there are no sharp edges on the tube which could damage the new silicon tube.
Nobby Clarke 211/05/2008 22:51:00
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Has the plane ever run through a full tank ? or is it a new set up.?
Ben Kelly12/05/2008 07:20:00
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no its never gotten through a full tank when in the plane but it has been thorougly run in on the test stand. The setup if fairly new, this weekend has only been the second time I have tried to fly it.
Tim Mackey12/05/2008 08:23:00
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Are you running a 2 x line or 3 x line setup?  Is the vent line clear, have you got the vent tubes (in the tank ) "curling" upwards and clear.
Ben Kelly12/05/2008 12:30:00
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its a 3 line setup but as the vent tubes are so near the top of the tank I didnt bend them upwards however when I take it apart to replace the fuel line I will bend those up aswell. Would leaving them straight cause a problem with the running of the engine?
Tim Mackey12/05/2008 14:59:00
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Only if you do a lot of inverted flight
Nobby Clarke 212/05/2008 18:19:00
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You say it only runs through half a tank when you fill it ,are you sure the tank is filling all the way to the top ?.

Your next step is to fill it and look to see if the tank is full.

If  your  vent pipe is straight then when fuel reaches the vent  its giving you a false reading because the vent is not near top of tank  The fuel doesn't have to reach top of the tank before it starts to flow down the vent hence why you are only getting half tank runs .

putting bends in the tank vent pipes will cure that ,but make sure they don.t touch the side of the tank so as to block them off  guess how  i know about that..!!!

Hope that makes sense

Ben Kelly12/05/2008 20:06:00
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i have watched as i filled the tank up to the vents as they are near enough the top of the tank to get it more than 3/4 full but the problem is when the fuel level reaches the halfway point on the way back down it just likes to cut out.
Nobby Clarke 212/05/2008 22:49:00
26 forum posts

Can't help feeling that the problem lies in the tank area ,replace all fuel lines replumb that tank.

Have a fresh start

Steve Hargreaves - Moderator13/05/2008 16:15:00
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It certainly sounds like a tank plumbing problem to me too. For the vents an old trick is to file a vee into the top of them. Even if the ends of the vents are pressed against the top of the tank then they can still..er...vent OK.

Make sure you clean it throughly before putting the tank back together though....brass filings in yer fuel equals a short engine life!!!! 

Are you using silencer pressure??

Ben Kelly22/05/2008 13:27:00
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looks like it was a problem with the fuel tube inside the tank, I re-plumbed it and have now been able to run the tank with the fuel level lower than the pipes and it runs perfectly. Now all thats left is to test fly it hopefully this weekend. Thanks for all the suggestions and help. Happy flying.
Tim Mackey22/05/2008 13:58:00
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Result !
Nobby Clarke 222/05/2008 17:54:00
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Nice one..!!

Glad you got it sorted

I was about to post and ask how you were getting on.!!

Owen Hailey08/07/2008 17:44:00
391 forum posts

Hi all.

The first time I tried a ABC motor It was the same old story as Ben, on the ground fine in the air dead stick after dead stick, and I tried all the same things but It turned out that they just need that little bit more running in than the old motors I was used to it is nice to have good advice on hand as often we do not now witch way to turn.

thanks everyone Owen.

jantrit09/07/2008 00:17:00
22 forum posts
Im having the same problem, with the same engine. Its in an irvine wildcard if anyone could help that would be greatly appreciated, heres the story: Firstly I ran 3-4 tanks through it, took it to the field and flew it around at about half throttle (would splutter if you messed with the throttle setting to much, although I expected this from a new engine) Then the problems began it started to cut in flight, some of the more experienced guys at the club had a look at the needle settings but still it would cut in flight. Then one of the guys had a look at the carb as it was sticking, and solved that problem. Then the high end needle fell out in flight, by this time I was about ready to go all electric. Then the threads on the bolts securing the carb stripped, so I bought a jen carb, they sent me the carb with the non-remote high speed needle. As I didn't want to wait around I fitted that carb and ran the fuel tubing from the tank straight to it. I also replaced the tank as I suspected a leak. With a brand new tank and carb I was sure that I had fixed all of the possible problems, and yet this time I couldn't even get the plane into the air, it would run perfectly on the ground , in the pits, but cut as soon as you added throttle to take off (this had happened a bit before the new tank and carb, but the plane would atleast recover and head skywards) By now I think this thing is scared of heights or something, Sorry for the long post but if anyone had any suggestions that would be hugely appreciated. Thanks Michael

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