Do you mean "where on the consist are the fuelling points" or "when running a service, where on the map do I go to get fuel"?
I've been carefully rationing this wonderful route's scenarios and services. Has someone come across any of these that involve fueling? I hope so!
None of the Scenarios or the 08 services require you to refuel. Not sure if there are 101 / 37 services where you do so.
This information should be useful -- and would be if the 2D map included track and area labels or, even better, if in 3D mode pressing one of the so-far unassigned keys would pop up those labels. What a hope!