1965 johnson 40 hp sudden power loss

[Paul Moir]

Re: 1965 johnson 40 hp sudden power loss

Yeah, if you've got a problem it's probably up in there. If it's a crankcase sealing issue, the only likely leaking spot would be the top crank seal which will also be visible with the flywheel off.<br />But I don't think that's the problem since it normally gives you an awful idle and doesn't affect WOT much.<br /><br />The thing about cracked coils and spark plug wires is the magento works harder and generates higher voltages as the RPMS increase. So often what happens is it won't arc over at low rpms and it runs fine, and then as the rpms pick up it dies. The engine slows a bit, and then it starts firing again. <br />Now sometimes that cylinder will 'mysteriously' kick in and out, giving you a sudden boost. So I'm still suspicious of something strange. Coils are the most likely candidate.<br /><br />Also, if you don't mind, trace the wire that comes off the center of the vaccuum cutout switch. It ought to run to the set of points that operate the bottom cylinder (the aft ignition coil). Wouldn't mind ruling that out.

 

[dafox99]

Re: 1965 johnson 40 hp sudden power loss

I think you have hit the nail on the head. I called my "sage on the mountain" guy that knows all things. he said the exact same thing .. it takes more fire at higher revs, and is probably arcing to ground or internally. it does the "cut out .. pick up" thing you described.<br /><br />I'll check the vacuum cut-out circuit as well. Just found two coils locally (not at my crappy shop). Will pick up tomorrow and install! I think this is it.

 

[dafox99]

Re: 1965 johnson 40 hp sudden power loss

Many thanks to Goodoleboy, Paul, and CATransplant. Runs like new!<br /><br />I replaced both coils, though only the the #1 was missing. It looked like new, though. I replaced the condenser and sanded the points and re-set. Points were waayy too close to begin with. Might have been part of the problem.<br /><br />Thanks again, guys.

 

[CATransplant]

Re: 1965 johnson 40 hp sudden power loss

Good deal, davef! If your points were set too close, that could certainly have caused your problem, since that also affects timing, and too close points tend to be erratic.<br /><br />Still, replacing the coils is a good idea. You should be set for another 30-40 years now!