Went flying today and could not keep my engine running during take off. On the ground, I did the pinchtest and made some small adjustments to where it was supposed to be. The engine increased when I pinched the fuel line like it should. But when I went to take off, it would die at about lift off speed. I checked it again and again on the ground and it was running great. very responsive and no problems at any throttle level. It only started choking and dying when it got up to speed. Also, there is fuel oozing out around the adjustment needle. Kinda strange. This engine was running great 3 days ago. the engine is a 2 stroke super tiger .40. any ideas???

When an engine was running well and suddenly starts acting badly, change the Glow Plug.

I think you should start with your needle valve, fixing the fuel leak, and also make sure the carb is on tight as well as the back plate is secure and there are no air leaks. I would also do as stated above by changing to a new glow plug. Make one adjustment at a time until the problem is fixed.

Good luck
Ryan

I will check for leaks tonight. I changed the glow plug at the field and it didn't seem to make a difference. I will check the backplate and carb for tightness. thanks guys.

The leak around your needle valve should tell you something. Check that are closely. When the engine gets under load, the leak at the needle is allowing air to get into the carb thus killing the engine.

Have you had any hard landings lately? You should also check the clunk in your tank to make sure it is not bent forward. If it is, the engine will die because as it picks up speed and the fuel goes to the back of the tank, the clunk only picks up air.

Rich

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Wyoming Wind Festival Jan 1 to Dec 31

Boy, could be a number of things. Leak in the needle valve sounds likely, but also check the glow plug, clunk, tear in any of the lines (in the tank and out). Are you using a fueling valve? Those often develope leaks.

I'd go along with Stamper, most probably a problem within the tank since everything was well for a long time. Could be a leak or break in the line just before it exits the tank or, the clunk is now rubbing on the back of the tank due to slight elongation of the tubing inside the tank.

Does that eng. have an "O" ring on the needle valve? If so it might be the problem with the leaking around the valve, then sucking air. ENJOY !!! RED

I agree with Rodney. I've seen it happen when the fuel line had softened and was close to the back of the tank to start with then will suck tight to the back of the tank on acceleration.
FEB

Try draining the tank from the fuel line to the needle valve. If the tank only drains half way then fuel line has come off inside the tank. It will run well, then quit as the fuel surges to the back of the tank. Another test is to hold the craft nose straight up and see if it quits. Same test as the other.
By George

I know his sounds simple but check your pressure line.
Same thing happened to me once when not connected.
Could yours be blocked somehow?
KW_Counter

Thanks a lot guys. This is my work email so I will have to try that when I get home. My fuel tank is a SOB to get out due to my battery and receiver possition. I think While I have the tank out to check it, I'm gonna make it a little easier to get the tank out. I used glued in balsa sticks to hold my elec. The air field is 5 min. away from my work and I plan on checking out things tommorow after I check/fix everything over. I will let you guys know what it was. thanks again!

there could be dust in ur needle valve thats what happend to mine now its runns better than ever!!!!!
touch wood

One problem could be a hole in the fuel tank. I'm sure it's something else in your case but a common mistake many of us make in our early RC stages is drilling into the tank. Not hard to do. Get the motor and tank installed then you start on your cowling,,grabbing the drill to make the holes for cowl screws and *%*$%$())%

Been there done that!!! [:@] Only have to do it once and then you'll never do it again. Of course when I did it I was getting ready to head for the flying field, no replacement tank, and the LHS a 45 minute drive away!!! What a way to ruin a day of flying. grrrrrrrrrr

Ken

Well, I didn't have to drill any holes after my fuel tank was installed. This plane is brand new and only has about 5 flights on it. I am already on my 3rd glow plug in 5 flights. uggg. It was about 25-30mph winds today so I didn't get to runway test it so I don't know if the new glow plug fixed it or not. Fuel lines where all in tact with no holes and everything checked out great. I'm guessing it was just do to a cheap glow plug. (red devil or whatever it's called). Again, it runs great on the ground, passes the pinch test, responsive at any throttle level, tilting it up everything it only when I am getting up to speed and trying to take off. The landings have been scary because it's a short runway and the engine dies either at the end of the runway during take off or right after take off. wheels down so far but not a choice way to land a kit built plane heading toward trees! Thanks for your help. I will keep everything in mind if the glow plug doesn't fix the problem.

Shouldn't ruin your flying. A short screw and a bit of glue will seal that hole up really nice. Don't ask me why I know this.

I've had that symptom several times. Idles fine, but dies at full throtle. It usually turns out to be a hole in the fuel line between the tank and the needle valve - an easy fix. I had one airplane/tank that had a rough spot where the hose had to make a turn to clear the motor mount. I deburred the brass tank tube inside and out with an X-acto blade and haven't had a problem since. That line takes a lot of "abuse" being pulled and replaced to fill the tank.

Only takes a tiny leak to kill the engine. When diagnosing a problem: start with the easy fixes, then move along to the inexpensive fixes.

To everyone that gave me input,

Last night I finally got to run my plane at the field. Turned out to be my glow plug was too short. Put in a new longer glow plug and it flew perfectly all night. This was the only problem. It ran better than ever. Not sure how it ever ran on the short glow plug. FYI. thanks for everybody's input. happy landings!