Fuel question

[Staticalliam7]

Is it possible to to have a tank drain to only a specific engine? 

[AHHans]

26 minutes ago, Staticalliam7 said:

Is it possible to to have a tank drain to only a specific engine? 

Only if you have a part that blocks crossfeed in between, e.g. a decoupler with crossfeed disabled. But if you have two engines connected to the same tank, then both engines will drain from that tank when they run.

What you can do is:

• Shut down an engine when you only want other engines to run. E.g. activate high-thrust engines only for launch and landing but only use high-Isp engines for in-orbit maneuvers.
• Deactivate draining from a tank at all (by clicking on the green triangle next to the resource display in the PAW.
• Pump around the fuel to the configuration that you want after (during?) the burn.

[Scarecrow71]

On 11/1/2021 at 8:02 AM, Staticalliam7 said:

Is it possible to to have a tank drain to only a specific engine? 

I'm going to assume that you have multiple tanks on your ship, but instead of putting engines on all of them, you want to just use 1 engine.  The easiest way to do this is to run fuel lines from the tanks with no engines to a tank with an engine.  The wiki has an entry on the FTX-2 External Fuel Duct, and the wiki page gives information on the fuel line.

FTX-2 External Fuel Duct - Kerbal Space Program Wiki

Now, if that's NOT what you are asking, then I either direct you back to what @AHHans OR I'll ask that you provide some clarification around your question.  And either way, happy spacefaring!