1975 50hp johnson no spark

[vanguard123]

Hello all. This is my first post and lets see how it goes.
These are the things I've done so fa,r and spring salmon are starting to come and no boat!
I have a 1975 50 hp johnson. One day the spark went away on both cyl.
1. I noticed one of the coils was cracked so I replaced with two new ones and new champion spark plugs.
2. I also checked all the ground wires and changed them on the engine.
3. found out rectifier was bad so I got a new one and installed.
ok, now I tried to start her up and no spark. But then after a few more turns of the key it starts. Idle it for about 5 min then turn it off. Turn it right back on and it starts. I walk away for about an hour and come back and try to start and no spark again.
4. Pulled blk/yellow wire from slot #5 on power pack and turned the key and no spark, put it back and no spark. Earlier on it started with the #5 wire disconnected or connected?
5. I tested the #1 wire on power pack to test the charge coil output. The manual stated it should read around (675-825 ohms) which mined check at around 715 ohms. So I guess that means the stator and charge coil are ok?
Could it be the timer base, or power pack? I really don't want to end up replacing everything if not needed. If someone could please recommend a next step for me to take I would be most grateful.
** Check the timer bases resistance and stator both came back good.
Again it started later on without me doing anything to it. Something is working at one point and then not at others.

[tashasdaddy]

take a look here. http://www.boatpartstore.com/page29.asp

[vanguard123]

Thanks for that web site. I've seen it before and ran those tests. All the tests on that site came back good. Well, I ordered a power pack and it should be here tomorrow. I will install and post back. Once I get this fixed I will post everything I did so to help anyone else in my shoes.