Looking for someone's ideas on a problem I have. We were flying my son's trainer the other day and when he would get it into a dive and I would take over control and level it back out, the engine would sputter and sometimes quit. I took out the fuel tank and checked the clunk-ok. When on the ground I would point the nose down and then up trying to recreate the problem but it would run fine. I also tried to richen it up a few clicks but that made no difference. The centerline of the tank is slightly lower than needle valve. Any input would be appeciated.

Where was the throttle when this was happening? And is he handing you the Tx? Maybe you are bumping the idle cutoff or something like that.

We were flying at about 5/8 throttle and using a buddy box setup.
I have flown YS for so many years I forgot about fuel supply problems. It is running the standard muffler with tank pressure. Also this was the first flight this year, ran perfect last year.

Did you change your glow plug at the beginning of this season? Although this sounds like it might be a fuel problem, having a fresh plug after a winter of storage and banging around can sometimes solve all kinds of problems. A broken plug filament will sometimes seperate only at times of added stress, causing intermittent firing. Maybe worth a try anyhow...

Is is YS fuel, or regular fuel? If that fuel is kinda old, it could be the problem.

The fuel is 15% Omega. I will try a new glow plug & fresh fuel next time out & see what happens. Thanks for ideas.