fuel loss

Need help. I have a 2008 311cdi which is losing fuel. I've traced the source to what looks like a long breather pipe which is located at the rear of the engine. It looks like it drops down and is routed around the bell housing before ending just above the front axle. a) Should this pipe be here...

Need some help. Horrendous fuel loss when going over 65mph. Fuel sprayed all over the underside of the van from the prop to the rear and over the back doors. MPG figures are ok when travelling long distances and keeping under this speed. Any ideas where I should be looking for the leak?