no spark
 

have msd 7al3 and crank trigger every time a throw my painless ignition switch i blow a fuse what could this be

Sounds to me you have a dead short somewhere. But the first thing that I would do is make sure everything is wired correctly. Then the best thing to do is get a volt/ohm meter and go through the process of elimination. Check your switch, check wiring making sure you don't have a bare wire. JMO.

TS1955

Have you used this system prior to this ?
Is this a brand new system and this is the first you've put juice to it ?