81 b2000

hey guys i have a 1981 mazda b2000 and the other day i started it to warm it up. it ran for about a minute then died no spark so i replaced the coil and still wont start . no spark while turning over but when you turn ignition off it sparks once off the coil wire i am stumped and need help asap thanks

With the key on, check for power at the coil.
If there's not 12 volts on the positive side, your ignition switch may be bad.

edit: If there are contact points in you distributor, they may be out of adjustment, welded closed, or just worn out.