Why does my BitTorrent never upload certain torrents?
There could be many reasons why your BitTorrent might not upload a torrent. Your firewall and router might be blocking incoming connections. Or, if a torrent is very popular, since there are so many more uploaders than downloaders, it would take a very long time before your client was asked to upload to anyone. On the other hand, if a torrent is very unpopular, there might again be many more uploaders than downloaders. The BitTorrent protocol is designed to just work without the user needing to think about it. If no one is downloading from you, your help in the swarm isn’t needed.