The Northern Irish pop star moved to America's West Coast several years ago and she set up her own bar, Irish Mist, in Orange County in 2008.
She has now revealed she considered joining the Starbucks franchise before deciding to focus on a bar/restaurant project during her hiatus from the girl group.
She tells Britain's Gaydar radio, "I was going to invest in a Starbucks. I tried to do the franchise... but I opened a bar-restaurant in California and we do lots of different coffees. I have never worked harder in my entire life. I opened a record label, I wrote and produced an album and did a distribution deal with a company I have huge respect for...
"I was more into a business frame of mind, rather than, 'I'm a singer'. I was more business minded and strategic so I love the fact I was able to do that and try something completely different."
Coyle has run into trouble with her American business project amid reports the bar will be auctioned off by authorities if she fails to settle a huge unpaid tax bill.