Info I found on Findagrave.com
Andy died 19 Mar 1985 and was buried in Oak Hill Cemetery in Battle Creek, Calhoun, Michigan.
There are several other Pupavacs listed in the cemetery that are most likely relatives.
Robert Pupavac b. 1888 d. 1947
Violet Pupavac b. 1902 d. 1944 (perhaps a sister?)
Jovo D. Pupavac b. Mar 20, 1880 states that he was born in Yugoslavia, d. Dec 27, 1941.
I would try and get an obit for Jovo. Andy might be his son or nephew.
Ancestry.com Michigan Death Index 1971-1996 also states that Andy was born Nov 14, 1903. You could see if he shows up on the 1910 census anywhere.
also on Ancestry.com in the US Naturalization Index, Andy naturalized on Aug 20, 1940 in Detroit. Birthdate is stated as Nov 8, 1904. Since he filled out his naturalization index, I would assume this might be a more correct birthdate. His petition #139011 will enable you to order this document. It could give you more clues. Good luck!