Direction of Current Flow: Coil to Amp? or opposite?

[ADK_Boater]

Hey everybody,
I have a 1972 Johnson 85hp that I'm trying to get to spark.
I'm still a novice and I was wondering if the current flows from the coil to the amplifier or the other way around? I have a Clymer manual but it lacks a lot of useful info. I can't even find the firing order in there. I did find it here in the forums as 1-2-3-4 thankfully.
Any help would be great. I'll get'r to spark one of these days.
Thanks!

 

[Daviet]

Re: Direction of Current Flow: Coil to Amp? or opposite?

I think you need to get a factory manual, maybe this will get you started.
http://web.ebscohost.com/serrc/pdf?...b513-e7b254b11f5b@sessionmgr112&vid=6&hid=122

 

[ADK_Boater]

Re: Direction of Current Flow: Coil to Amp? or opposite?

I wish, but I think I'm starting to exceed my budget. I guess I need to figure out the wiring diagram a little better.
Thanks for responding. I did some tests today and they went well. I tested the coil output and I had a good steady spark. I tested the breaker points with a multimeter and the reading dropped from 12.6v to 1.5v when the flywheeel reached the timing marks... at least as best I can tell they were lined up. Next I will test my plugs to see if they get spark. Previously they did not but maybe I didn't have them grounded properly. Be back with the results of that tomorrow...

 

[Daviet]

Re: Direction of Current Flow: Coil to Amp? or opposite?

Remember that you have a dist cap and rotor under the flywheel that transfers the spark from the coil to the plugs.

 

[ADK_Boater]

Re: Direction of Current Flow: Coil to Amp? or opposite?

Hmmm...They appeared to be ok when I re-gapped my breaker points. I burnished them with 400 grit. I didn't do a resistance test though...didn't think of it. If I can't get spark to the plugs, then I guess I'll take the flywheel back off and do some investigating. That is very helpful. Thank You.

 

[Daviet]

Re: Direction of Current Flow: Coil to Amp? or opposite?

What did you set your points to, .010?

 

[ADK_Boater]

Re: Direction of Current Flow: Coil to Amp? or opposite?

Yes. I lightly burnished them with 400 grit. They looked good, no pitting. However, I was confused about how to set to the proper gap. At first I thought that they needed to be .010" when they are closed, and then they widen out and return to .010" so on and so forth. I tried looking here in the forums for that info and returned to points and set them to .010" at the widest point, and making physical contact otherwise. I hope that description made sense. I'm still not 100% sure that I did that the right way. lol

 

[Daviet]

Re: Direction of Current Flow: Coil to Amp? or opposite?

The points should be open .010 when the rubbing block is on top of the cam lobe and be closed when the rubbing block is not on the can lobe.

 

[ADK_Boater]

Re: Direction of Current Flow: Coil to Amp? or opposite?

Then I got it right...the second time. I'm glad I didn't leave them the way they were and put everything back together.
What is the best way to to proceed now If I want to get the plugs to spark?

 

[Daviet]

Re: Direction of Current Flow: Coil to Amp? or opposite?

By the way I read your posts, your coil is firing a good spark. That would tell me that the problem has to be down stream of the coil. The only things down stream of the coil is the dist cap, rotor and wiring to the plugs. I would find it hard to beleave that all your wires are bad at the same time. When you checked the coil for spark, where did you check it, at the coil itself or at the end of the coil wire where it screws into the dist cap?

 

[ADK_Boater]

Re: Direction of Current Flow: Coil to Amp? or opposite?

At the end of the coil wire where it would thread into the cap. I fastened that to one end of the spark tester and grounded it with a 2 gauge battery cable (that's all I had) to the head. That leads me to believe the coil wire is ok...at least I hope.

 

[Daviet]

Re: Direction of Current Flow: Coil to Amp? or opposite?

If you had good spark at the dist end of the coil wire, your problem is further down stream, cap or rotor. To my way of thinking the rotor accepts spark from the coil and distributes it to the posts in the cap. Then the dist cap sends spark to each plug. The rotor has a little piece on it that fits into a notch on the crank that times it to the dist cap and makes it rotate. Does your rotor seem to lock onto the crankshaft?

 

[Daviet]

Re: Direction of Current Flow: Coil to Amp? or opposite?

Another thought, I have seen cases where the rotor would arc to ground and kill the system.

 

[ADK_Boater]

Re: Direction of Current Flow: Coil to Amp? or opposite?

Yeah, that would be really bad! I didn't know that, but while I was setting the points I cleaned the point on the rotor (if you call it a point) with 400 grit and also cleaned the metal surfaces on the in side of the cap, the ones that the rotor would energize while it rotates. I hope that would prevent arcing to ground. I made them all shiny if that helps. Thanks for the heads up on that. I'll definitely post the spark plug test results tomorrow. I'll use the spark tester this time since I have one now. Before I grounded the plug to the head. Not the best idea but I didn't realize it was so dangerous at the time.

 

[ADK_Boater]

Re: Direction of Current Flow: Coil to Amp? or opposite?

I meant to get back about the results yesterday but my friends Mercury 115 Saltwater (he uses it in freshwater) had an electrical fire and I had to go out and tow him back in. He's an electrical engineer so it was kind of ironic. His motor definitely looked terrible when we got back. It smelled like burning plastic and and was covered in fire extinguisher discharge.
So, I got sidetracked with that yesterday and today because I had to Tow him to the marina this afternoon so he could trailer it over to a repair shop.

Heres the result. I didn't have the spark plug wire boot over the cap so it was arcing to a bracket. Once I put it over the fitting, the plug sparked beautifully. I'm thrilled! Now I have to custom make a few new wires (I'm ordering a small kit here on iboats). I accidentally broke two wires. I went to my local Evinrude/Johnson marina but they only had one compatible wire in their old stock.

Thank you Daviet! I hadn't considered that it might have been arcing. Now I just have to find out why it is not getting fuel. I'm good with that end of things, so I will troubleshoot that tomorrow. If I have trouble there, then I will start a new thread.