my buddy wanted me to hook up the fuel line in my boat with a 3 way tee about 3 weeks ago. i all most did , after asking about this topic in the winter I decided to go with the 3 way valve . i was going back and fourth in mind witch way to go . I PM L&M (Hank) and ask his opinion , he said if no valve or check valve in line serious damage can happen . now that being said if i ask Fran Barrett and he told me the same as he told Frogger i would have went that way too. I am not sure if it makes a difference if its outboard to out outboard or like what i have i/o to outboard . Any ways i went the 3 way valve and it is working just line , i do think i will miss not being able to run both motors at the same time if needed .