His show was shonw in the evenings around time as Magnum PI, he just wasn't as popular, I am not sure if he was American or European.
aladdinwa
Pierce Brosnan played private detective Remington Steele in the 80s.
.
Louie O
From 1985 - 1988 Robert Urich played a detective in 'Spencer: For Hire'.
http://en.wikipedia.org/wiki/Robert_Urich
Or maybe Paul Michael Glaser, who played a detective in 'Starsky and Hutch', but that was in the 70's (1975 - 1979).
http://en.wikipedia.org/wiki/Paul_Michael_Glaser
LilyRT
pierce brosnan actually played a PI in an 80s series called Remington Steele. could that be what you're thinking of?
http://www.imdb.com/title/tt0083470/?ref_=nv_sr_1
Steel
I would have initially guessed "Remington Steele" myself, but since that wasn't it, maybe it was "Hart to Hart" with Robert Wagner?
http://www.imdb.com/title/tt0078622/?ref_=nv_sr_1
DeeDee
Matt Houston (ABC TV series from 1982 -1985)?
Synopsis:
Matt Houston stars Lee Horsley as a wealthy mustachioed Texas oilman named Matlock "Matt" Houston who worked as a private investigator in Los Angeles in his abundant free time. The show also starred Pamela Hensley as his lawyer sidekick, C.J., and George Wyner as his continuously frustrated business manager. During the show's third and final season (1984–85), Buddy Ebsen joined the cast as Matt Houston's uncle, Roy Houston.
EDIT: How about one of these?
Jake and the Fatman (1987–1992) https://images.search.yahoo.com/images/view;_ylt=AwrB8pPOmC5Vq38AdFKJzbkF;_ylu=X3oDMTIzM2szbmlmBHNlYwNzcgRzbGsDaW1nBG9pZAM1NjY2NDIzOTJmYjI2MWNiOGFhYzM4MDE2ZmEwZjQ0YgRncG9zAzM1BGl0A2Jpbmc-?.origin=&back=https%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3DJake%2Band%2Bthe%2BFatman%26fr%3Duh3_answers_web_gs%26tab%3Dorganic%26ri%3D35&w=326&h=400&imgurl=joepenny.unas.cz%2Fobrazky%2Ffoto%2F16_1_b.jpg&rurl=http%3A%2F%2Fwww.joepenny.unas.cz%2FJAKE.htm&size=35.1KB&name=%3Cb%3EJAKE+AND+THE+FATMAN%3C%2Fb%3E&p=Jake+and+the+Fatman&oid=566642392fb261cb8aac38016fa0f44b&fr2=&fr=uh3_answers_web_gs&tt=%3Cb%3EJAKE+AND+THE+FATMAN%3C%2Fb%3E&b=0&ni=168&no=35&ts=&tab=organic&sigr=11430i8cu&sigb=13b38ih7i&sigi=118j67218&sigt=10q6mdflv&sign=10q6mdflv&.crumb=WZkeGpQ4el4&fr=uh3_answers_web_gs
Hardcastle and McCormick (1983–1986) https://images.search.yahoo.com/images/view;_ylt=AwrB8pPOmC5Vq38AdFKJzbkF;_ylu=X3oDMTIzM2szbmlmBHNlYwNzcgRzbGsDaW1nBG9pZAM1NjY2NDIzOTJmYjI2MWNiOGFhYzM4MDE2ZmEwZjQ0YgRncG9zAzM1BGl0A2Jpbmc-?.origin=&back=https%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3DJake%2Band%2Bthe%2BFatman%26fr%3Duh3_answers_web_gs%26tab%3Dorganic%26ri%3D35&w=326&h=400&imgurl=joepenny.unas.cz%2Fobrazky%2Ffoto%2F16_1_b.jpg&rurl=http%3A%2F%2Fwww.joepenny.unas.cz%2FJAKE.htm&size=35.1KB&name=%3Cb%3EJAKE+AND+THE+FATMAN%3C%2Fb%3E&p=Jake+and+the+Fatman&oid=566642392fb261cb8aac38016fa0f44b&fr2=&fr=uh3_answers_web_gs&tt=%3Cb%3EJAKE+AND+THE+FATMAN%3C%2Fb%3E&b=0&ni=168&no=35&ts=&tab=organic&sigr=11430i8cu&sigb=13b38ih7i&sigi=118j67218&sigt=10q6mdflv&sign=10q6mdflv&.crumb=WZkeGpQ4el4&fr=uh3_answers_web_gshttps://images.search.yahoo.com/images/view;_ylt=AwrB8qBzmC5VUUQAbaeJzbkF;_ylu=X3oDMTIzcjlpM29jBHNlYwNzcgRzbGsDaW1nBG9pZAMzZTlhMzUyZTEyM2I3YWM5NDU3OWZjNjk3NGE1NjQ2YQRncG9zAzI1BGl0A2Jpbmc-?.origin=&back=https%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3DHardcastle%2Band%2BMcCormick%2B%25281983%25E2%2580%25931986%2529%26fr%3Duh3_answers_web_gs%26tab%3Dorganic%26ri%3D25&w=320&h=240&imgurl=fe.img.v4.skyrock.net%2F3118%2F7493118%2Fpics%2F554500831.jpg&rurl=http%3A%2F%2Fnostalgie-tv.skyrock.com%2F554500831-Le-juge-et-le-pilote-Hardcastle-%26-McCormick-1983-1986.html&size=15.8KB&name=Le+juge+et+le+pilote%26quot%3B+%28%26quot%3B%3Cb%3EHardcastle%3C%2Fb%3E+%26+%3Cb%3EMcCormick%3C%2Fb%3E%26quot%3B%29+%2A%2A%2A+%3Cb%3E1983-1986%3C%2Fb%3E+-+Le+...&p=Hardcastle+and+McCormick+%281983%E2%80%931986%29&oid=3e9a352e123b7ac94579fc6974a5646a&fr2=&fr=uh3_answers_web_gs&tt=Le+juge+et+le+pilote%26quot%3B+%28%26quot%3B%3Cb%3EHardcastle%3C%2Fb%3E+%26+%3Cb%3EMcCormick%3C%2Fb%3E%26quot%3B%29+%2A%2A%2A+%3Cb%3E1983-1986%3C%2Fb%3E+-+Le+...&b=0&ni=72&no=25&ts=&tab=organic&sigr=1347d9vmc&sigb=148lk8cq8&sigi=11lhlqdve&sigt=13beacg1p&sign=13beacg1p&.crumb=WZkeGpQ4el4&fr=uh3_answers_web_gs