I suspect that the handwritten name "Rack" in the marriage record has been mis-interpreted and that it was actually "Back" - which is a common name. In that case there is the following passport information in the Finnish Migration Institute's database:
Detailed passport information Last nameBack First namesKarl Johan Michelsson Other names* Date of birth. .9999 Marital status* Religion* OccupationEnt. taloll. pka Home parishNärpiö ProvinceVAA Passport date19.09.1891 Passport number0 Passport valid (year:month)4:0 DestinationAmerikka Passport issued byKR RemarksAge: 16.
Sadly Karl Johan lost all of his family, his father Michel died on 5 Oct 1875, mother Caisa on 26 May 1885, his sisters Maria Gustava in 1876 and Johanna Karolina in 1889. Apparently he then decided to go to America, the communion book only has the note "has been away since 1890".