Dave,

Is it normal to have air bubbles in the fuel line between the regulator and carburator?? When I go from idle to full throttle, there are a few air bubbles in the line, then they clear out after a couple seconds.

The reason I ask, is that yesterday my YS .91FZ decided to flame out on me after takeoff without warning, engine was running perfect up until then. After landing in the freshly plowed field and ripping the landing gear off, I decided to run a couple more tanks with the plane in its carrier to try to troubleshoot.

After a fresh tank of fuel, the engine would run great - 2000 idle, 8900 top end. . . then at high power the engine would cough a couple times and quit. Hook up the glow plug, turn it over and it would run perfect again. It did this again at random times, but always at high power setting.

Up to this point, I had broken the engine in with two tanks though it in my back yard and it worked well there. Today, I ran two tanks again in my back yard and it worked great, also except for the air bubbles while transitioning?

Is there anything I should check for before I go out to try flying it again?

Thanks!!

Almost forgot: Cool Power 15%, OS F plug, 14 x 10 APC

The bubbles are normal. Usually if they cough and die, the top end is too lean. Back it off a couple of clicks and see if it still does it.

Hopefully the rain will quit soon so I can tell you!! Thanks!!