How do I stop fuel crossfeed?

[MrCMoney]

Ok so I haven't played this game in literally a year so I was just testing out some new mechanics in sandbox before I started the career mode. But then I noticed that for some reason I always ran out of fuel before I got into orbit. After a few more tests I realized that My third stage liquid fuel was being drawed into my second stage liquid fuel. I have no idea why this is happening because my decoupler says that it won't allow fuel crossfeed. I've tried fixing it for about 90 minutes and now I think that I'm going to give up on this game because it's kinda a game-breaking bug for me :/.

[Red Iron Crown]

Welcome aboard!

Right click the tank and disable it by clicking the little green arrow. I'm betting you're using some sort of jet engine or RAPIER, those ignore crossfeed rules. Can you share a pic of the vessel in question?

[Nich]

The TA-18A stack seperator? As a workaround you can turn off your third stage tank then turn it on after you separate. I have had some instances of tanks supposed to be on radial decouplers were actually clipping the center tank and I would get cross feed.

[A_name]

Apart from what others said, you might also want to take a look at the Tweakable Everything mod.

[MrCMoney]

Welcome aboard!

Right click the tank and disable it by clicking the little green arrow. I'm betting you're using some sort of jet engine or RAPIER, those ignore crossfeed rules. Can you share a pic of the vessel in question?

I don't think that I'm using a jet engine.

http://steamcommunity.com/sharedfiles/filedetails/?id=461923978

[sal_vager]

Actually, you are, the Rapier engine has a jet mode and due to limitations in fuel flow logic, it is able to draw fuel from the upper stages.

You're better off with an aerospike to be honest.