1975 Mercury 650 starter issue

[Dr. Noodles]

I have a 1975 Mercury 65 hp that now has a starter problem. There might be a couple of issues but I have eliminated the major ones. The starter was bad so it has been replaced along with the solinoid . The starter will spin but does not rise up and engage the flywheel. It will if jumped directly to the battery. I have cleaned and tightened all the connections from the solinoid to the starter and still it just spins! One thing I did was installed a battery switch which functions fine ...I was thinking maybe the wrong gauge of wire inside the box? Not enough voltage. The battery is good.
Any suggestions would be appreciated!
Thanks , this is my first boat and has been fun up till now!

 

[Chris1956]

Mercs of that vintage have a battery cable for both positive and negative on the starter. Make sure both are clean and tight to get max voltage to the starter. Make sure the ground cables from the lower cowling to the engine midsection are clean and tight as well.

 

[The Force power]

In addition.... if these Battery-cables are original? replace them with suitable gauged Such as #4
(perhaps the switch is the cause?)

Also it is not the voltage that is required to crank the starter but amperage
Imagine a kink in the garden hose water, it reduces the amount of water but it still makes it wet.
unrestricted waterflow will put out a fire

 

[Dr. Noodles]

In addition.... if these Battery-cables are original? replace them with suitable gauged Such as #4
(perhaps the switch is the cause?)

Also it is not the voltage that is required to crank the starter but amperage
Imagine a kink in the garden hose water, it reduces the amount of water but it still makes it wet.
unrestricted waterflow will put out a fire

Thanks! You know I pulled a piece of electrical tape off of the large battery cable running from the battery to the solenoid and it is pretty chewed up under there . That could be the problem. So 4 gauge wire is sufficient? It's got to be something between the battery and the starter because jumped straight from the battery there is no issue.
I'll let you know. Thanks!

 

[Dr. Noodles]

Mercs of that vintage have a battery cable for both positive and negative on the starter. Make sure both are clean and tight to get max voltage to the starter. Make sure the ground cables from the lower cowling to the engine midsection are clean and tight as well.

Thanks Chris, I pretty much checked the connections but won't hurt to do it again. I had a fit with the trailer lights for the same reason. Every light worked ...but not in the right sequence, until I found that "magic ground" fault!!
Thanks for the tip. It's gotta be something between the battery because it works fine when jumped.

 

[merc850]

Put your voltmeter on the battery terminals and turn it over - then put it on the starter terminals and turn it over, the voltage should be the same (approx. 11v) if it's low the battery is weak or the solenoid connections are not clean.

 

[The Force power]

So 4 gauge wire is sufficient?

YES

 

[Dr. Noodles]

To everyone who offered their assistance on my starter issue thank you so much! It turned out that the Force Power was correct. I checked the battery cables as I mentioned and they were pretty bad so I replaced them...she started right up!! Like I said it's my first boat so this site is a great help... I'm learning!

Cheers!!