4.3 Mercuiser Thunderbolt IV testing

[zbaker]

How do you test to see if the Thunderbolt IV is good or bad?
Im getting no spark
Replaced coil and the wire to the distributor. When I start cranking it over, after about 15 seconds, it trips the small breaker next to the ignition. Thoughts?

 

[04fxdwgi25]

Hope this helps

 

[Scott Danforth]

troubleshooting guide in the stickies at the top of the forum