I just did the NH03 - Fuel up and then run Light Engine to Manchester Victoria timetable service on NTP, and was very disappointed that you couldn't actually refuel the loco. There is a service about refuelling, and yet you cant refuel. All you do is stop at the pump and then keep going. I jumped out of my train and the game was telling me to start moving again. The pumps are there, they just need to let us actually use them. Perhaps this could be something added when the preservation crew gets around to NTP.
There are plenty of scenarios where you have to refuel. Pen Corridor has them and I'm sure there's a UK one with the 66, so I'm sure it could be properly implemented there.
Scenarios are different from timetable services. There is a refuel service in Cumberland Yard in SPG and it works in the same way because of AI limitation.
I don't know if its possible, but could it be done that AI services stay the same, but adding the option to actually refuel for the player?
I can't remember if you can actually "refuel the locomotives" in NTP or not, but you can always stop there, get off and use the pump. I'll check that real quick. EDIT: Just checked it. I was able to use the fuel pump and connect the hose to my loco. However I couldn't actually "refuel" it as the pump was stuck after connecting. Looks like another issue is found.