Do NOT Turn back to the runway
There have been two recent Kitfox accidents where there was engine trouble and the pilot and passenger were killed attempting a turn back to the runway.
The Kitfox is not particularly prone to this accident as lots of a/c will also kill you if you attempt the same.
But one does not hear so much of this accident type in certificated a/c these days. The ultralights do seem to have more engine problems.