15 hp Johnson Project

[Bullie]

My nephew asked me to see if I could get his Johnson 15 hp model 15R76A running. He said it doesn't have spark, and he was right. I tested at 7/16 and moved in to 1/8 and never got any spark. There is some surface corrosion on the coils. I have not pulled the flywheel off yet. What should be my first move?

I bought a new compression gauge and apparently it sticks at 60 lbs. I tested 3 motors, one I know has 125 lbs compression, and they all maxed out at around 60 lbs. So, I am not certain of the compression as of yet. But, the Johnson showed more compression than my known compression engine (125 lbs) on the gauge. If that means anything. I will take the gauge back and get another asap.


I know this isn't the right forum for this question but maybe you guys can help me out with another motor. I picked up a 9.9 Chrysler Sea King this weekend. It doesn't have any spark either and it will not shift into reverse. I pulled the LU off and could only push the linkage rod down far enough to engage reverse once. After pulling the rod back up into neutral and forward it could not get it to go back into reverse. LU oil looks good. Impeller is good. Any advice you guys can give me on this one is appreciated too.

 

[boobie]

The first thing to go for on that motor is the breaker points. That ignition system is a bear to work on.

 

[F_R]

Agreed, clean the breaker points shiny bright, and set gap to .020" Especially that Chrysler. Those develop a fuzzy corrosion on the contacts that looks like mold. That stuff is non-conductive and has to be removed.

Are you spinning the prop as you try to shift it to reverse? Something has to be moving in order for it to snap into reverse gear. No problem if the motor is running.

 

[Bullie]

They look almost new.



The coils...not so much.

 

[Bullie]

No F_R I wasn't spinning the prop. Just checking things out on the little Chrysler. It looks to be in good condition. Just no spark. It sounds like I should worry about other things before the shift issue, as it probably isn't an issue. I haven't pulled the flywheel on it yet. I will work on that and get some pics for you guys so you can guide me.

The flywheel popped right off the Johnson. I was very surprised given the effort needed to get the flywheel off the Evinrude you guys helped me with recently.

 

[Bosunsmate]

Pull the coils and clean the bolt grounds.
Have you opened the points and checked that they arent pitted?
Check there is no continuity to ground from corroded wires between the points and the coils (do this when coils are undone.)

 

[Bosunsmate]

Lift up the charge/stator coil too and check that either blue wire has being squashed and is shorting to ground, or any other abnormal looking sign on it

 

[Bosunsmate]

Whats the kill circuit on that one?
Have you disconnected the stop switch? they can often ground out,
im just thinking that since its both cylinders id suspect charge/stator coil or a grounding out somewhere

 

[Bullie]

I had time only to get the flywheel off last night. This motor has a kill switch in the front.

Thanks Bosunsmate. That gives me a list of things to check. I will go through the things you have listed and report back.

 

[gm280]

I have to say that you have posted some very good pictures that most never do. Amazing shots of the ignition system. These close up shots should be examples for others to follow for providing shots of their ignition issues. Having said that, it looks like the spark coils, especially the top one, looks like it has a crack in it. So I would look at replacing them both if it were mine. Also if the points look good and/or clean up nicely, do check the condensers as well. Because if one of them is shorted, you will never get that engine running... Also the exciter coil looks really corroded and needs a good cleaning to make good ground. If that doesn't clean up and check out good, replace it also... It is better to repair/replace anything that just doesn't measure up correctly ONCE, and forget about it and go boating, then to constantly be going back in there to fix another suspect part. And apply some lube to the point rubbing block areas or crank lobes so they don't prematurely wear out so quick or change gap. JMHO!

 

[Bullie]

The pictures really help me understand what you guys are trying to explain. Helps me greatly to make sure we are talking about the same things. It looks like both spark coils have a hairline crack. How do I check the condensers?

 

[F_R]

Great pictures. But I go back to my original reply and tell you to clean the points. They may look fine, but they develop an almost invisible corrosion on the contact surfaces that is non-conductive. On this Lo-Tension magneto, BOTH sets of points have to be making perfect contact in order for it to have spark. That is because one set has to be making contact with ground while the other set breaks it's contact with ground.

There is no electrical connection between the driver coil and the laminated core. Or at least there better not be. Therefor, the bit of corrosion you see at the mounting screws means nothing. Same goes for the spark coils

Cracked secondary coils may or may not be a problem. I'm betting they are not. But they could fail in the future, so it isn't a bad idea to replace them.

Again, polish those points shiny bright before you go crazy taking everything apart looking for something more exotic.

EDIT: Make sure the ground wire between the armature plate and ground is secure and clean. Also, the ground wires on the spark coils need to be removed and cleaned up. All those wires need to be making good electrical connection. Last but not least, the disconnects in the blue wires must be making good contact. Corrosion is not good contact.

 

[Bullie]

F_R, definitely going to do just what you said and clean the points first. Will I need to put the flywheel back on completely to check the points. I assume I will have to spin it to see if a spark is being produced.

 

[gm280]

Bullie, do you know how to use a volt/ohm meter (DVM VOM) ? If so remove each condenser lead and set the meter to ohms and one lead on the wire lead from one condenser and the other meter lead to ground. If the meter reads zero, that condenser is shorted. If the meter reads and the needle or digital readout goes up, then the condenser seem to be okay. If the meter reads nothing, then the condenser is open... Do the same for both condensers. If both read about the same, reconnect them back to their original place again and move on to the next thing. This should be a wiring schematic of how that ignition system is wired

 

[OptsyEagle]

Will I need to put the flywheel back on completely to check the points. I assume I will have to spin it to see if a spark is being produced.

You can put the flywheel back on and just tighten up the flywheel nut very snug and check for spark by pulling the starter cord. Just make sure the spark plugs are removed and as long as it doesn't actually start up, you don't need to torque down that flywheel.

Once you get spark then make sure you torque it to spec. I think it is around 40 to 45 ft/lbs, but check a manual or ask others, to be sure.

As FR stated. If that motor has sat for 3 years or more, those points will be corroded and will not produce spark. Give a good cleaning with a points file and then set them to 0.020" gap. Then dip a clean white business card in lacquer thinner and pull it through the points and then blast them with compressed air and then don't touch them. I bet she sparks fine after that, although those coils did look a little nasty. If it was mine, I would replace those, even if I got spark but they probably will work the way they are, so I will leave that up to you.

 

[Bullie]

Thanks for the advice. I kinda have the green light (within reason) to work on this motor. My nephew figures the coils are bad and told me to fix it if I could. He is going to pay for my education, so to speak. I plan to follow all the advice I have been given, especially the attention to the points, and clean things up some.

 

[boobie]

I'll stick with what I said in post # 2. If there's any question about the condensers, just replace them. It takes a special tester to test them properly.

 

[Bullie]

I cleaned the points as you guys instructed as well as the condenser and coil ground connections. We have spark! It will jump a full 7/16ths on my tester.
I dropped the LU, cleaned and inspected the water pump housing and checked the impeller. The impeller has a set but is still quite flexible. I will replace it before returning the motor but I believe it will suffice until I determine if I need to order any other parts.

Is there something else I should do before seeing if I can get it to start?

 

[Bullie]

Bullie, do you know how to use a volt/ohm meter (DVM VOM) ? If so remove each condenser lead and set the meter to ohms and one lead on the wire lead from one condenser and the other meter lead to ground. If the meter reads zero, that condenser is shorted. If the meter reads and the needle or digital readout goes up, then the condenser seem to be okay. If the meter reads nothing, then the condenser is open... Do the same for both condensers. If both read about the same, reconnect them back to their original place again and move on to the next thing. This should be a wiring schematic of how that ignition system is wired

I could get no reading on my meter through the condenser. Honestly, I do not know if I did it correctly.

 

[Bosunsmate]

Is there something else I should do before seeing if I can get it to start?

Go ahead, do a drop test on each cylinder early on so you can be sure one cylinder isnt running dry,