Re: 1958 18 hp johnson. Wont start when hot.

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Posted by Ed Mc. ( on July 05, 2005 at 19:07:20:

In Reply to: 1958 18 hp johnson. Wont start when hot. posted by Tim Ross on July 05, 2005 at 16:02:52:

Check to make sure that the mag plate bushing isn't worn. If the mag plate rocks too much the points gaps will change drastically and this will affect spark quality.

But it really sounds to me like the coils might be giving out.

Unless you have newer coils you can't be sure.

If you have older coils with any cracks at all, or material oozing out of them, they are shot.

You can get new coils from for under $13 each, it might be worth replacing.

The heat might just be too much for the poor old thing!

P.S. when it dies you should pull the plugs and check for a strong spark. If you have good spark at that time you may have other issues.

And do you have a pressure tank? Maybe the hot temps are overpressurizing the tank and flooding the motor out. If you had a marginal carb inlet needle/seat it could leak enough to flood out the motor.

HTH and let us know what you find.........ed

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