Smoke and Fire particle problem

Can someone tell me why the fire stops about 50 frames before the end of the animation?

How do I add more fuel to the fire as it were?

Blendfile can be downloaded from here: http://files.mjhooper.co.uk/s/jj33gKv8F8MlGCi

In physics tab property for Smoke Domain object there should be Smoke Cache. Change outlook thereabouts.