Weak spark

[Red Rider]

I have two older Evenrude engines without a lot of hours on them. One is a 1966 6hp and the other is a 1971 9½hp. Both of these engines have always been kept as emergency power on sailboats and other than starting them several times a year they don't get ran very much. <br /><br />Both motors are getting had to start, and had a very weak spark. I replaced the points, condensers, and plugs on them this weekend. (The old parts didn't look bad at all). <br /><br />The new parts didn't do much to solve he problem.<br /><br />I took the flywheels off again and performed the highly technical, and sophisticated magnet test. (You know where you hold a screwdriver to the magnets in the flywheel and see if the screwdriver is attracted to it). The magnets are weak, which explains the very week spark.<br /><br />Is there anyway to re-power the magnets or should I just buy new flywheels?

 

[Paul Moir]

Re: Weak spark

You would have to replace the flywheels.<br />Are your ignition coils free from cracks in thier insulation? It is a very common source of problems with those older johnny/rudes. Iboats sells replacements (pn 18-5181) for around $17 each, which deliver a nice hot spark.<br />Other common sources of weak spark:<br />Incorrectly adjusted timing.<br />Incorrectly positioned ignition coils.<br />Dirty points. (clean with acetone or MEK or something like that)<br />Use of automotive 'Supressor' spark plug wire rather than the proper metal core stuff.<br /><br />I hope this helps!<br /><br />EDIT: It is possible to remagnetize the magnets if they are the problem. A very old Johnson/Evinrude shop may have the Stevensons machine to do it, or you may construct your own if you have the required electrical skills. But weak flywheel magnets are relitively uncommon and I would be surprised to find you have two with problems.