According to his website http://www.jamesmarvell.com/home.html, he was called by Christ to become a country singer and to keep kids off drugs. He formed Country Cavaleers and that singing duo disbanded in 1976.
Marvell went solo in 1976 turning his attention back to Gospel Music and the original calling on his life which only got stronger in 1973 when he accepted Jesus as Savior through the ministry of Bob Harrington aka The Chaplin of Bourbon Street. In 1974 James met another powerful minister who inspired him greatly, evangelist LeXXXXX XXXXX. He began making special singing appearances on the LeXXXXX XXXXX Crusades all across America during the middle to late 70s and even took a musical program to a South Carolina prison in the 80s to perform for Jenkins and his other co-inmates.
Hope that helps.