#4 cylinder plug not firing on my 150 Intruder

[sapo]

I noticed after running my engine for a while the #4 spark plug stops firing. I bought a new dual coil and spark plug and it does the same thing. Once the engine gets hot that plug does not fire.Any suggestions 1995 150 intruder 60 degreee block

[ELGIN]

Model and Serial number?

[Lockjaw]

Does it fire properly when the engine is cold, and then quit working once it warms up? If you let it sit for a while, does it work again?

On my engine, my powerpack was going bad. Engine would start cold and run fine to my first spot. stop and fish, crank it up, and about the time I got on plane, the port side of the engine would lose spark.

I think you are going to have to get out a voltmeter and a manual and do some testing. If it turns out the be the pack, be careful with the RFI shield, it will cut your finger if you aren't careful.