I have a MTD rider that blew a 17.5hp briggs single cyclinder and replaced it with a used 19.5 twin cylinder motor. I ran the motor about 1 1/2 hours and it started missing then died. The coil is definetly bad no spark, my question is was this just bad luck the coil failed or was it compatability from the 17.5 to the 19.5. The only wiring difference was the the 17.5 had a going to the carb fuel bowl and the harness connectors had to e spliced. I also slipped the coil from the 17.5 onto the unit and hooked up to one cylinder and fired off immediatley so I am pretty sure I have the wiring correct.

 

If it does not fire with the kill wire removed and it is gapped properly, the coil is bad. You didn't say what engine you have, so all I can say is if it's a flathead opposed twin, the coils are famous for going bad.

 

be careful that wire splice to the solenoid on carb isn't some how wrong and allowed 12v to the coil kill wire. If so you'll burn out the next coil