1.15.2
Pipes are going into the right hole.
Pipes are facing the right direction.
Pump is powered and facing proper direction
Only mods that might be causing a problem are Silent's mechanisms and iron jetpacks.

Strange. That shouldn't be the case. Will close this for now. Let me know if this happens on newer version of the mod (1.16 or above).

I've tested with the exact setup and it's working on my end. Maybe you changed the mode of the pump by right clicking it with a wrench. Can you try an isolated test by only installing the vehicle mod?

I've tested with the exact setup and it's working on my end. Maybe you changed the mode of the pump by right clicking it with a wrench. Can you try an isolated test by only installing the vehicle mod?

I've done multiple tests on superflats. I've come to the conclusion that its probably the world itself.