In the past we have had issues with the facebook integration and the solution was to disconnect your facebook account from your fuelly account and then reconnect it again. It had something to do with a timeout due to time limits and facebook's policies.
Facebook just recently made some changes to their APIs so we'll also need to upgrade the system on our end for those. We are planning to launch a new backend for Fuelly in a few weeks so we'll table the work on the Facebook API until we are on the new system as the developer for the old system is no longer available.
Sorry for the inconvenience and thanks in advance for your patience.