1973 Johnson 4 HP no spark

[dukboat]

My kids keep bringing me the projects! They picked up a 73 Johhny 4 hp at a yard sale for $50, the motor looks like new, inside and out. Tried to start and found it had no spark, pulled flywheel and checked coils,(no cracks) look new, set point gap to .20 put flywheel back on still no spark, pulled flywheel again and checked whith a ohm meter I have continewity between where the coil wires attache to the points and ground, direct short right, like when you want to shut a motor down. Any help would be great. Thanks Dukboat

 

[Crosbyman]

Re: 1973 Johnson 4 HP no spark

great motors !! flywheel off do you see point open and closing ? cam in place ?? and is key pin on the shaft ??

 

[dukboat]

Re: 1973 Johnson 4 HP no spark

Yes to all, points were gaped to .20

great motors !! flywheel off do you see point open and closing ? cam in place ?? and is key pin on the shaft ??

 

[nwcove]

Re: 1973 Johnson 4 HP no spark

How to test a coil in an antique outboard engine - YouTube

 

[dukboat]

Re: 1973 Johnson 4 HP no spark

Thanks, One coil tests bad the other good, I should have spark on the one cylinder with a good coil I don't.

How to test a coil in an antique outboard engine - YouTube

 

[nwcove]

Re: 1973 Johnson 4 HP no spark

Clean the points till they are spotless.

 

[Crosbyman]

Re: 1973 Johnson 4 HP no spark

sparks will come but why not check compression and if OK

revive that great motor with a set of frsh coils, points,condensers. (about 70$) cheap for a good kicker !

 

[boobie]

Re: 1973 Johnson 4 HP no spark

The only proper way to check a coil is with a load tester. I've seen coils that ohmed out okay and still broke down under a load test.

 

[tomhath]

Re: 1973 Johnson 4 HP no spark

with a ohm meter I have continuity between where the coil wires attache to the points and ground, direct short right, like when you want to shut a motor down.

When the points are closed the coil is grounded, when the points open the circuit from the coil to ground should be open. If there's still a short when the points are open start disconnecting things until you find it. Could be the terminals connected to the points, could be a wire with insulation rubbed off, whatever. Nothing mysterious about it, just a short circuit somewhere you'll find with the ohmmeter.

 

[dukboat]

Re: 1973 Johnson 4 HP no spark

Replaced both coils, gaped points put in new plugs fired up on third pull runs good Thanks