50hp Johnson Intermittent starting problem

" I just got a used pontoon bo

" I just got a used pontoon boat with a 50 johnson on it. The model is 50ESL74M. Sometimes, seems to be only cold, it will not start. It has no spark.The motor came with a 1972 service manual and a 1974 parts catalog. When comparing the two the ignition systems appear the same so I am using it for troubleshooting and specs. Signal, charge, and ignition coils checked out OK as well as all grounds and connections. When this motor runs it sounds great. After working on it late afternoon it started and ran fine. Later in the evening nothing again. I thought about the sun shining and warming it up so I heated the powerpack with a hair-drier for approx 15 Seconds and it fired right up. I used to use this trick in reverse to find bad modules on cars. I was able to do it again the next morning(no spark-heat it up-great spark). I am new to outboards and know better than to assume but does this sound like a bad powerpack? Are there any other tests I can do? If it is the pack and I change it will it affect the timing? Thanks for any help!! "

"Rick.... You would be well ad

"Rick.... You would be well advised to keep that hair dryer away from that powerpack. The beginning of the ignition system is under the flywheel (Stator/Charge Coil Assy), a dual purpose component. Small coils for charging, the larger coils supply approx 300v AC to the pack.

If that stator is cracked, and/or leaking down, the voltage being applied to the pack will drop resulting in a erratic, and eventually a non operational powerpack. Sooooo check that stator visually for defects.

If all is well there, with the s/plugs out, and when you're sure you have no spark, disconnect the black/yellow wire from the powerpack and check for proper spark. If you have spark now (should jump a 7/16" gap), the usual cause is a failing ignition switch (shorting out the kill circuit).

NOTE... The flywheel nut torques to 105 foot pounds.

Joe "

" Joe,
Thanks for the reply.

" Joe,
Thanks for the reply. Forgot to say in previous post that I tried cranking with the black/yellow wire disconnected and had same problem. I did not visually check the stator however, the ohms readings were good(16.2 on sensor coil-867 on charge coil). I will visually check the stator when I get back to the boat. What do you mean by leaking down? When I have spark it jumps 1/2" gap very strong. Assuming the stator looks good Any ideas why it will spark after slightly heating the powerpack? Being new to outboards is there anything special about removing the flywheel other than the tourqe(thanks for the spec)?
Thanks again and your expertise is very much apprieciated.
Rick "

" Joe,
By the way the reaso

" Joe,
By the way the reason for the hair drier is there were intermittent ignition/die- out problems in the early to mid 1970's automobiles that were caused by thermal failure of the ignition modules. We used these to verify/diagnose these weird problems. This seemed a little to familiar and about the same time frame.

Thanks again
Rick "