fuel/water separating filter question
 

Hello all. I have fuel separator/filter housing that appears to be able two handle dual tanks as it has 2 inlets and 2 outlets. Being I only have 1 tank, two of the ports (1 in and 1out) have brass plugs screwed in to them. After draining the lines when rebuilding the mechanical fuel pump I removed 1 bass plug in the hope that the new filter would fill with gas by gravity and then I could replace it and prime the pump and be done. All is well except the brass plug has a drip now. It looks like the other one has putty on the threads.
My Question is what type of putty is appropriate and would Teflon tape be better? If thread tape which type? I assume the white stuff for water wouldn't be good but would the yellow kind for natural gas pipes stand up to gasoline? Can't have a gas leak so I need to get this right. Any help appreciated. Thanks

I would just use a swipe around the threads with Permatex #3 (Aviation grade). IME, it has better gasoline resistance than #2 and it still flexible.

You can used teflon tape as well, Teflon has good resistance to both gasoline and ethanol. However, you have to be really careful the teflon never gets to the end of the thread, especially if it's after the filters. It can get in a place where you don't want it... and since it has good chemical resistance, it does not dissolve and just plugs stuff up. I only use teflon where I'm stuck in situation were I don't have the proper solution... and the alternative is worse.

+1 on #3 permatex...it has a brush so is easy to apply on the threads.