Hello. I have about 10 flights on a Kadet Senior with an OS 40 LA. The engine has run beautifully the entire time. My instructor suggested I run her a bit rich for awhile. My last two trips to the field have resulted in 4 "glider" landings. She starts fine, runs ok, and then just quits. She doesn't lean out or sputter, just runs well, then dies. I watched it for a while and did notice a bubble or two. I changed glow plugs and that didn't seem to help.

I'm thinking the fuel went bad, some suggested vibration is causing foaming. I thought about going to a smaller tank (8 oz) to get more foam around it. It's not set too rich I don' think?

I'm getting frustrated and any advice would be appreciated. Thank you.