Did u fixed animations of pumps, to attach to locomotive? Cuz diesel locomotives were missing animation of pumps while refuel.

No, no animations at this point. the mod works by placing a normal fluid tank below the locomotive that the pumps connect to like pipes - that's why there are no animations at the moment. If I find the time i'll look into it, but no guarantees

Place the fluid wagon under locomotive?

I believe that was the old implementation that was later replaces by the tank-based implementation for stability reasons. I won't do anything that would significantly reduce stability or performance. I am however considering a few possibilities. While not a priority at the moment I'll look into it.

I was making realization of such feature, easiest way - create temporary invisible fluid wagon if locomotive stopped at fluid based refueling. Make nth tick event to pass fluid from fluid wagon to solid fuel placeholder in locomotive. Then your animations works fine and stable, sadly i cant provide codebase, but iam sure you got what i mean. You can check how to teleport fluid wagon on locomotive in train teleportation mod. Anyway hardest feature would be to check fluid wagon fuel inside value.

thanks for the hints. it's on the list. i have quite a lot on my plate currently, so don't expect it soon, but i will certainly look into it when i have the time. And reading the wagon content is trivial - it's just a simple fluidbox like any pipe or tank. A bit more tricky may be filtering empty wagons.

I would provide an code base if i have time in future.

It's possible to set somebody as collaborator:

I would provide an code base if i have time in future.

I looked into the old diesel locomotive code from version 0.15 that still used fluid wagons. I think i can build on that. give me a week or two for the implementation

Hi, I'm the original author of the old diesel locomotive. The ability of placing hidden fluid wagon was actually removed by Factorio developer, because of my bug report no less. Back then, I was using hidden fluid wagon and hidden rails with different "rail-category" with the regular rails. Theoretically it should prevent disturbance to the regular rails but apparently it is coded in different way than I thought. I posted a bug report and the ability to place overlapping rolling-stock (train-wagon-like entities) is removed altogether. Here's my original bug report, https://forums.factorio.com/viewtopic.php?f=23&t=49820

hey thanks for the information! i guess that closes that path for now. Maybe i'll find another way my manually animating the pump arm somehow.