Is it OK to bump a question that received not enough attention (tumbleweed candidate) to the top using an edit?
If so under which circumstances?
Bumping questions, in the sense of pushing them to the top of the active list by editing them, is always encouraged. As long as the edit in itself is valid!
Editing a question solely for the purpose of bumping it, without providing further information or otherwise improving the question, is strongly discouraged.
This is exactly what bounties are intended for. How bounties work is outlined in detail in the FAQ, in the section What if I don’t get a good answer?.
First of all, nobody is stopping you from promoting the question. Feel free to share it on your favorite social network or let a friend have a look at it.
That being said, you can also join us in Chat and discuss the question. Maybe someone else has an idea on how to improve it. Maybe someone even knows the solution or likes the question so much that he/she bounties it.
Lastly, questions automatically get bumped by Community if they're inactive for a while.