I've been flying my Sig Senior Kadet w/K&B .61 2C for a couple months now with good luck... The other day I dinged the nose strut on a hard landing and had to replace it and add some plywood to the firewall to reinforce it... Nothing major, just part of the game... After the repair, I successfully flew the airplane one time... On the next flight, everything was going well until I went full throttle in the air... The engire ran fine at first, then after 2 - 3 seconds it leaned out and died.... I was able to get back on the ground dead-stick without damage... I chalked it up to experience, refueled and tried again... This time, when I took off I got to about 50' AGL at full throttle and the engine leaned out and sputtered... I throttled back and the engine returned to idle, but wouldn't throttle up again, just sputtered and died... I was barely able to get back on the ground in one piece... I then put the airplane on the test stand and duplicated the problem... The engine starts fine, runs fine at low RPM, but when I throttle up it runs fine for 2 - 3 seconds and then dies...

I replaced all fuel lines... Still does it...

I reset to a richer mixture... Still does it...

I checked the clunk in the tank... Attached and functional... Still does it...

I'm at a loss...

Any ideas???

Thanks,

Mark

Make sure the carb did not loosen. Also, you said you checked the clunk and it looks ok. Was the clunk line one of the ones you replaced? Perhaps the impact put a pin hole in it. Watch for air bubbles in the line when it's running. You also could have gotten something in the needle assembly. Try removing the needle and the fuel line and attach a fuel line to the needle side so you can use air or fuel to flush it out.

It also could be an air leak at the carb as previously indicated.
Also perhaps a leaking crankcase gaseket.

Just some ideas,
Ryan

Try changing the glow plug.

Could also be some dirt lodged in the carb limiting the fuel flow. Remove the needle valve and squirt fuel through to flush it out.

It is hard to believe no one checks the Glow Plug!!!!

Same thing happened to me this past weekend. A new glow plug fixed it.

That may not be the cause but it's the easiest thing to try!

I Had that prblem... Ironically <SP?> After a hard landing... I ran fine just as you said 1-2 flights then nothing... Turns out it ingested a bug which was stiing on the needle vavle..Musta been hungry

mdavis223> Like you said, idle speed is constant but your engine cuts out when the throttle is fully opened . That simply means that your engine is running too lean. It doesn't get enough fuel (either on a high end or a low end). Try to open the high speed needle valve. If it still flames out, open the low end screw counter clockwise. If it doesn't work, there must be any leaks somewhere. Fuel Leak or air leak also makes the engine run lean. Anyhow, make sure that both needle valve and carburator are clean.

to make sure your settings are correct on the engine pinch the lines.. the motor should stay at the same rpms and then die... if it goes to higher rpms then dies im pretty sure its to lean?

This is not true.
During a pinch test you want the engine to speed up slightly. This is a slightly rich setting and is desirable. If you pinch the fuel line and the engine stays the same or dies, it is on the lean side and should be richened a click or two.

Thanks for all the advice guys...

That's the nice thing about this forum... If it's happening to me, it's bound to have happened to someone else before...

I'll try the most obvious things first, like changing the glow plug, cleaning out needle valves on the carb and re-adjust the mixture again... I really don't want to pull the tank if I don't have to since it will require minor surgery to do so...

It's just so strange though... One day it runs fine, the next nada...

I'll vote for the carb leaks air. I'd pull the carb off(and flush it out) ,clean the crankcase opening and carb spigot, and reinstall with some silicone sealer. Those crankcases are a bit weak around the carb locking screws and have a tendancy to crack and warp causing air leaks.

Check your high speed needle to see if its loose. Run the engine up at full speed and see if the needle is moving on you. This is a common thing also. Like they also said on the clunk. On your nose landing the clunk could be stuck up in the front of the tank. Also the fuel line where it goes onto the brass of the tank could be split from when you hit and the tank was push forward.