According to our records we sent out four messages to your Facebook account—your last four fuel-ups. From our end it looks like everything is working fine.
You might try re-authorizing Fuelly to post to Facebook. It's possible that if you changed some application/privacy settings after authorizing Fuelly it won't allow posts.
Start by removing Fuelly on the Facebook side. Go to Application Settings and look for Fuelly. Click the x on the far right to remove.
Now add Facebook again here. Go back to Fuelly and click 'Settings' on the left side of the page. Scroll down to 'Social Integration'. Click the reset link next to Facebook. The page will reload, scroll down again, then click 'Authorize Fuelly on Facebook'.
Once you run through this you could try adding a fake fuel-up to see if you have a connection.