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Thunder tiger pro 46 ran great now stumbles help

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Thunder tiger pro 46 ran great now stumbles help

Old 08-22-2013, 03:46 PM
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gbfan
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Default Thunder tiger pro 46 ran great now stumbles help

I did not do anything different. I went to the field and and the engine started fine and when I
held it in the air, it started to stumble. It sounds like the engine rpm is surging. I checked for air leaks Even
removed the tank and blew air into it. No leaks. No air bubbles Then I tried a new glow plug os # 8 !! Adjusted high speed needle
everywhere. Went back to 2 1/4 turns and started there. still the same. removed the needle and tried some
thread tape. No Luck. running on same fuel as last week It ran fine then. Puzzled . who is the expert here... help
David
Old 08-22-2013, 08:09 PM
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jeffie8696
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Try checking the carb for a fuel blockage, then check all the nuts and bolts.
Old 08-22-2013, 10:44 PM
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Remove the needle and blow or pump fuel through.
Old 08-23-2013, 02:34 PM
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gbfan
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I checked for blockage by blowing compressed air through the needle and the the carb but it still has a problem, but its not surging on the ground any more ! When I put it in the air by hand.
It starves for fuel. On the ground it runs fine, high end is ok, low end it goes right to full speed idles fine. You would not know there was a problem till
I put the plane at a 90 degree angle in the air she runs for a minute even if you put it back down it dies.
The o ring on the needle is the original Would this o ring sucking a little air do this ??? only answer if you are sure of this please . I also tightened the head bolts I am not able to reach the crankcase
bolts as I would need to remove the engine That might be the next step as I might try another engine that I have. This one had similar problems an another p[lane as I remember .
Thanks
david
Old 08-23-2013, 03:49 PM
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Sounds like it is just leaning out as the tank level gets lower. Bigger carbs are more sensitive to vairiations in level. If raising the nose leans it out, it is normal. Just richen it a couple of clicks. Could also be a plugged muffler pressure nipple or so many other things. Oh, I answered and may not really know. If the air is getting sucked in the needle, then there is no muffler pressure because it would be leaking out.
Old 08-23-2013, 04:36 PM
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It really could be a number of things. the good news is Glow engine are so simple - they need air, fuel and heat to run. To much or not enough of either and you will have problems. So, checked for blockages, checked for leaks, checked the plug..... how about a pin hole leak in the tubing being uncovered when the nose is up? But it could also be the o-ring. You are probably going to have to eliminate things one by one
Old 08-23-2013, 04:37 PM
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gbfan
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Hey there I will try putting a full tank to see if it leans out when its full ! It dies from lack of fuel when at 90 degrees As far as rich goes I think I am already at 3 1/2 to 4 turns on the rich side already . I will
look at that muffler pressure nipple. I checked it still feels like good compression I can barely hold my finger on the glow plug hole and it becomes a little hard to
turn the prop but I don't have a gage... As far as your statement about air getting sucked maybe I am not getting enough muffler pressure under full load at 90 degree to pump the fuel all the way straight
up do to a small air leak in the needle valve???
Old 08-23-2013, 04:41 PM
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gbfan
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Heres what I see ! When I hold the plane at a 90 degree straight up at full throttle it stumbles and starves for gas and the engine
gets hot and dies.... is this normal ?? Or can an air leak in the needle valve oring cause it not to be able to pump enough fuel
to keep the engine running. it takes about 30 to 60 seconds for it to die . and if I bring it down sooner it still makes it stumble. I know a fuel tank issue could cause this but I am quite sure of the tank and the lines as they are new and no leaks there.. or what else can cause this condition as it runs fine till I put at 90 degrees ?????
Thanks David I don't think this could be normal as A big loop in the air would cause the engine to stumble.








altered which o ring are you referring to I have been talking about the needle valve o ring

Last edited by gbfan; 08-23-2013 at 05:16 PM.
Old 08-23-2013, 06:31 PM
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Sounds to me like it's running lean when nose up, which could be due to an air leak - either past the needle oring or somewhere else. My enya 60 was acting like this - it would run great for a minute or so then die. While I run her on an airboat, and don't get her pointed up, the principal is the same..... I richened her up a fair bit and the problem solved itself. Anyway, Do one thing at a time until you narrow it down.
Old 08-23-2013, 07:35 PM
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Why do you hold it up 90 degrees for a whole minute anyway. I think anything would lean out and die for that length of time. Is it a huge tank or too far back maybe?
Old 08-24-2013, 06:38 AM
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gbfan
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Maybe not a whole minute seems like a long time when engine is screaming ! no 10 oz tank
right place according to manual right behind engine
Old 08-24-2013, 06:58 AM
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gbfan
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Why would you think any engine would die while at 90 degree? I have seen people hover for several minutes.
The fuel IMHO should have enough back pressure to reach the carb even at 90 degree. This after all is not
a gravity feed fuel sytem. Am I right ?? I did ckeck the pressure fitting and it looked ok .
Old 08-24-2013, 07:22 AM
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Are you flying it? I just go at 45 degrees for 20 seconds and fly if it is ok. I would keep it over the field in case of a deadstick because of previous experiences. The guys that hover a lot do have it quite rich when doing that.
Old 08-24-2013, 11:27 AM
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Tank pressure when around half empty is why you have a vent line from the muffler to the tank.
Old 08-25-2013, 12:12 PM
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gbfan
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I think I found the problem I changed to a colder plug os # 10 and also tried new fuel ...

Ran great right from the start !!

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