When i run the pump(ANY LIQUID), it will flow to the pipes and then crash!
It says on the crash log, Description: Rendering Entity in the World, java.lang.IllegalStateException: Already tesselating!
CrashLog --> https://pastebin.com/gEd56xgm

BuildCraft version: 7.1.10
Forge version: 10.13.4.1614
Singleplayer or multiplayer: SinglePlayer
Additional information:
2560 / 4000 RAM for Minecraft
Processor: AMD Sempron(tm) 140 processor 2.70 ghz
RAM: 4GB
64BIT OS

looks like an optifine issue, try removing that

also BC 7.1.10 is extremely outdated (by about 2 years), please update to the latest version (7.1.23) as that has many bugfixes and improvements

Turns out... it was an optifine issue, i dont want to remove optifine so i did is, i turn the chunk loading to default instead of smooth. And now its working fine. Thnx! :)

is there anyway i can fix this problem without messing with optifine or removing optifine?.. i've already updated buildcraft, thnx in advance

not from our end, this is optifine messing with fundementals of how things render and that goes wrong sometimes with other mods

you can try contacting the optifine dev but i doubt 1.7.10 is still supported