Starter wiring question for my 1985 Mercruiser 170

[Provincetown boater]

Hi Folks,
I am a newbie here but I am a bit mechanically inclined. I have a 1985 Ebtide with a 170 mercruiser. When I got this boat 5 years ago it had never seen the ocean now it lives in it all summer and near it all winter, so stuff has been happening to it.
Last year the starter was sized after the winter nap and I had a local mechanic replace the starter and slave solenoid. After working on it for some 3 hours he could not get it to turn over, so he threw up his hands and sent me on my way.
I found a second mechanic who was not much better but working with him we were able to get the new starter to turn over, but only by bypassing the slave solenoid. I lived with this for last summer, but I had intermittent trouble with the starter and so this year I decided to go back to the real problem, this time myself.
After re instating the original wiring and testing the slave as good, but with not so much as a click, I focused on the "purple - yellow" lead which according to the wiring diagram connects to the positive side of the ignition coil. For the life of me I could not understand how this worked. Then I found the post on this form by "Don" showing how that terminal should be connected to the ground. Thinking that made sense I ran a test wire from ground to this terminal and disconnected the "purple-yellow" wire. Turn the key and the engine turned over like it was brand new. Yippee
But now what do I do? How can this circuit work as shown on the diagram and what should I do to make this work?
Thanks for reading this long post and your help

Pete

 

[stonyloam]

Re: Starter wiring question for my 1985 Mercruiser 170

Hi Folks,

I focused on the "purple - yellow" lead which according to the wiring diagram connects to the positive side of the ignition coil. For the life of me I could not understand how this worked.

Hay Pete, Not 100% sure but I think that the wire to the coil provides battery voltage directly to the coil during starting, bypassing the resistance wire. The function of the resistance wire is to drop the voltage to the coil during normal running conditions, however when you are starting the boat the current draw by the starter drops the battery voltage, and if you did not bypass the resistance wire you drop the voltage even more resulting in a weaker spark, just when you need a strong one.
Let me think on the rest of you question

 

[stonyloam]

Re: Starter wiring question for my 1985 Mercruiser 170

I had a local mechanic replace the starter and slave solenoid.

Hay Pete: He put in the wrong solenoid! The one he put in does work exactly as you say. The terminal you attached to ground was correct..... for that solenoid. The solenoid he was supposed to put in grounds through the bolts that attach the bracket to the engine, and when activated puts 12 volts to the starter and the coil.

Check out Mercruiser manual #8, section 4-A pages 3 & 4. the solenoid on 3 is yours, and the one on 4 is the one you are supposed to have. Thanks for the puzzle.

This is the one you need (I know replaced mine yesterday) #11 http://www.mercruiserparts.com/Show...nbr=10&bdesc=STARTER+MOTOR+AND+WIRING+HARNESS

 

[stonyloam]

Re: Starter wiring question for my 1985 Mercruiser 170

Thought about it a little more (gotta get a life). If you added the p/y wire to the r/y terminal and ran a wire from the other terminal to a good solid ground (like the bracket bolt) you would accomplish the same thing. Full battery voltage to the coil when starting and good ground for solenoid function. Should work.

 

[YeboGogo]

Re: Starter wiring question for my 1985 Mercruiser 170

Thought about it a little more (gotta get a life). If you added the p/y wire to the r/y terminal and ran a wire from the other terminal to a good solid ground (like the bracket bolt) you would accomplish the same thing. Full battery voltage to the coil when starting and good ground for solenoid function. Should work.

I was just thinking the same thing.

I also had this problem over the weekend. Now the fix seems easy.

 

[Provincetown boater]

Re: Starter wiring question for my 1985 Mercruiser 170

Thanks everyone for your response and support. Here is an update.
The joining of the p/y and the y/r on the slave did not work since the starter started to turn over immediately after the key was turned to the on position. (Current flowing from the coil triggered the solenoid). I then moved the p/y to the negative terminal (unused), on the starter solenoid. She turned over slicker than ever before and once I put on the muffs the engine started up on the second try. I started and stopped the engine about 10 times while running it for about 45 minutes, do I dare say problem solved?
Now I am moving on the patching and bottom paint then launching next week
Those strippers are already waiting for me and I can't keep em waiting much longer

Thanks again

Pete

 

[fishinpa]

Re: Starter wiring question for my 1985 Mercruiser 170

Thanks everyone for your response and support. Here is an update.
The joining of the p/y and the y/r on the slave did not work since the starter started to turn over immediately after the key was turned to the on position. (Current flowing from the coil triggered the solenoid). I then moved the p/y to the negative terminal (unused), on the starter solenoid. She turned over slicker than ever before and once I put on the muffs the engine started up on the second try. I started and stopped the engine about 10 times while running it for about 45 minutes, do I dare say problem solved?
Now I am moving on the patching and bottom paint then launching next week
Those strippers are already waiting for me and I can't keep em waiting much longer

Thanks again

Pete

Well lets not keep those "strippers" waitin on anything then. lol

 

[stonyloam]

Re: Starter wiring question for my 1985 Mercruiser 170

Congratulations! Go get em!

 

[Shianajames]

Having a issue with my 1985 mercruiser brand new starter and slave solenoid but sometimes it will start just fine and other times it will keep the starter engaged with the key off what can it be caused from

 

[Eric 3.7LX Alpha 1]

Having a issue with my 1985 mercruiser brand new starter and slave solenoid but sometimes it will start just fine and other times it will keep the starter engaged with the key off what can it be caused from

Don't hijack a 12 year old thread from someone else with a different engine. Start a brand new thread of your own. Post your engine, year, serial number in your post and we can help you with your problem.