1971 Johnson 100hp Starting Questions

[oregonfish]

OK....went out to try to diagnose some electronic shifting issues, and started having starting trouble. I love a good project, but come on!!!

Here's the issue:
I can start the motor or at least get it to turn over several on several attempts (about 6-7 times). After starting the motor and shutting it off a few times, the starter stops working. This has happened several times, and after I wait a few hours, the starter begins working again, but only for those few times. When not working, voltage check is as follows:

Battery-12.6v
Red on top of starter solenoid, black grounded- 12.5v with key in "off" position. Key in on position reduces this reading to around 3v.
Red on bottom of starter solenoid, black grounded-0v even when cranking.

Jumper cables: One cable from positive of battery to power on starter does nothing. If I put both cables on the battery, ground one to the block, and put the positive on the starter power cable, the starter spins quickly, but does not engage the flywheel.

None of this makes sense to me. Why would the power decrease on the starter solenoid when I turn the key on? Why would the starter engage the flywheel sporadically, but not when jumped?

Please help! Tough to figure out the shift problems when I can't get it started!

Thanks,
Chris

 

[Daviet]

Start off by removing and cleaning both battery cable connections. Clean all the electrical connections on the solenoid and recheck your voltages.
Most starting problems are dirty connections.

 

[oregonfish]

Re: 1971 Johnson 100hp Starting Questions

Is it normal to have the voltage drop on the starter solenoid when the key is in the on position? Is there a reason the starter would not engage the flywheel when jumped, but does otherwise? Should I need to ground the jumper cables to the battery in order to get a response from the starter.

I will re-check connections, but answers to these questions will help me work through the issue. If anybody knows the answers to them, I would really appreciate it!!!

Thanks again,
Chris

 

[oregonfish]

Re: 1971 Johnson 100hp Starting Questions

Somebody must know the answers to these question! I appreciate the help!
Thanks,
Chris