Johnson Seahorse 3 having problems

bsorrells

Recruit
Joined
Jul 8, 2010
Messages
3
I recently purchased a 12' aluminum boat with a Johnson Seahorse 3 motor (made in the 1950's). The first time I used the motor, it worked great. It had been sitting all winter and took a few minutes to start up, but ran really well. Since then, it's been nothing but trouble. I've tried taking it out three different times and the results are different each time. The first time it started, ran great for a little while, then it started raining (dropped in temp) and it barely ran faster than the trolling motor. The second time it ran good for about 100 yards. Then just slowly started cutting out. The third time it didn't start at all...and most of the pulls the motor wasn't even catching. I replaced the spark plugs when we got the motor. I'm trying to figure out if it has something to do with high elevation since the first time was at a lower elev. lake (4000ft) and the last ones were higher (7000ft+) or if it's needs some repair. If it needs repair I might just have to buy a new one since most repair shops charge $100/hr. Any ideas?
 

sandbg1

Cadet
Joined
Jun 15, 2010
Messages
15
Re: Johnson Seahorse 3 having problems

I have a 1959 3 hp seahorse. I was having the same problem. Mine had a cork float in the carb. they all pretty much had them back then. I changed the float and valve. Adjusted the carb. used a little starting fluid. checked for spark and it fired right off.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: Johnson Seahorse 3 having problems

If you haven't checked the coils, that absolutely should be the first place to go. You have all the symptoms. They are notorious for cracking from old age.
 

Attachments

  • Cracked coils2.jpg
    Cracked coils2.jpg
    67.8 KB · Views: 0

Daviet

Fleet Admiral
Joined
Sep 24, 2008
Messages
8,958
Re: Johnson Seahorse 3 having problems

Check the spark and compression first, if they are both ok, move on to the carb. The carb may need to be cleaned after it sat so long. The carb has manual adjustments for high and low speed, so it an be adjusted for any elevation.
Make sure the tank is clean, the on/off valve is working properly. You are opening the tank vent, correct?
These motors are very simple to work on, I would suggest you get a manual so that you can preform your own service.
 
Top