'74 Johnson 70 hp

jackdpricejr

Cadet
Joined
May 1, 2010
Messages
7
Hey my father in law just gave me a boat and it has a 1974 70hp Johnson on it. the story as told to me by him is that the boat ran great then the powerpack went out and he had his uncle replace it and put it in the water and it ran great again went straight to his home about 2 miles upriver got to his home and idled down and he heard an "electrical" pop and the motor went dead would turn over but not start. before the uncle could come back he passed away and the boat has sat there for about 10 years. I am waiting on my manual to get here do yall have any ideas on where i should start looking? possible a bad wired powerpack? any ideas where to even think about begining would be greatly appreciated.
I know that i will be getting carb kits and new spark and probably new fuel lines. thanks
jack
 

Daviet

Fleet Admiral
Joined
Sep 24, 2008
Messages
8,958
Re: '74 Johnson 70 hp

Make sure your battery is in good condition. Check all electrical connections, make sure they are clean and tight. Make sure all wiring is in good shape with no bare spots or damaged insulation. Your manual should have a trouble shooting section that will help you check out your system.
 

Jet Wrench

Petty Officer 3rd Class
Joined
May 26, 2010
Messages
97
Re: '74 Johnson 70 hp

I've got a 75 70 HP. You need to check the round rectifier above the power pack. This is a problem area. There are 3 leads that come from underneath the rectifier that go to the black terminal strip. They make a tight bend radius to the strip and over the years, the insulation will break, expose the wire and corrode. I was lucky and able to repair mine, but I have a feeling I will need to replace it eventually. This is a good place to start. Check all of your grounds as well. Very important! Take your time and give it a good visual inspection. These engines are rather simple electrically speaking. Not much to them. The rectifier is about 40.00, the power pack is around 110.00.
 
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