old johnson outboard

bonitaboy

Seaman Apprentice
Joined
Feb 27, 2003
Messages
34
I have a old johnson outboard that is a 15 horse seahorse.I am not sure what year it is.It is model #fd-10,serial#1348448.I believe it is between a 1958-1968.It is in incredible shape but seems to be holding back a little bit on the power.I am running 50 to 1 oil ratio and unleaded fuel.I didnt know if a lead additive is needed or if it could be a carb adjustment or what.Any help on the age and problem?
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: old johnson outboard

Ahoy, John Doe.<br /><br />Your engine is a 1956.<br /><br />The recommended mix is 24:1, no lead additive.<br /><br />Good luck. :)
 

bonitaboy

Seaman Apprentice
Joined
Feb 27, 2003
Messages
34
Re: old johnson outboard

jb thanks for info,any ideas on why it seems to want to take of like a streak of ----and then settle back into a decent pace of speed.it has 2 idle and speed controls on the front,maybe out of whack or something,also wondering if the alloys it is made out of will hold up to salt water.
 

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
Re: old johnson outboard

Hi John,<br /> If it's lurching into warp speed, then dropping back to a slower speed, then it's likely you have an ignition problem. Take a look under the fly wheel and see if the coils are cracked. If they're shiny plastic, then they've likely been replaced at some point, but if they're cracked or chalky looking, replace them. Replace the points and condensers while you're in there.<br /> Run it on a steady diet of 24:1 fuel mix. High test fuel isn't necessary, but I usually stick with 89, as it seems to be a more consistent quality than the 87.<br />- Scott
 
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