Hello everyone,

I have a YS 140DZ mounted in a DP Edge 540 swinging an APC18x8W prop at 8800 RPM, Running CP 30% Heli. Engine has 4 gallons of fuel threw it.

Here is my problem:

Engine performs perfectly on the ground, idles great, high end is perfect. When flying the plane all works well. Ok here is where it gets funny.

If you go full throttle vertical or any RPM range vertical and cut back to idle while still vertical the engine loads up and stalls out. I test on the ground and it does the same thing, hold the plane straight up, go full throttle then back down to idle while still holding plane vertical and it loads up and shut down. Now I've backed the low end regualator screw counter clockwise to lean the low end out and that's still not helping.

Fuel lines running from the tank are single line running from tank to carb intake, second line is for venting, this is not a pressure sytems since I have a pump. All fuel lines are brand new, line connecting on engine are in great shape. I have not changed anything but leaning out the low end, checked glow plug and looks fine, can replace if need be but don't want to start doing things without a clear understanding of why I have this problem.

The engine runs great as long as you don't go vertical and but back to idle, if you go vertical just have to leave 1/4 throttle and she will continue to run.

Any ideas?
Should I just wait till the end of the flying season and send back to YS?

Thanks for the help,

Any ideas???

Where is Dave?

It is either sucking a bubble or the clunk is up against the back of the tank. Are you using the foam clunk?

Hey Dave,

Troy Newman lives in the Atlanta area and he came out and spent a few hours looking over everything. We ended up finding a small hole in the pickup line inside the tank about a 1/4" past the rubber plug. That would explain why at vertical she won't idle..

Replaced the tank and all is well.

Thanks Troy!!

And thanks Dave for responding..