'77 70 hp Johnson sensor wires

boatdumb

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Oct 29, 2003
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is there someone who can tell me if the Sensor wires should have current going through them when the engine is being turned over? :confused:
 

ob

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Aug 16, 2002
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Re: '77 70 hp Johnson sensor wires

If you are speaking of the temp sensor leads,they complete the ground circuit for alarm in the advent of an overheat.You will read some voltage on the tan wire when the key is in the "on" position or cranking.Why do you ask?Are you having some trouble with your overheat sensors or alarm.
 

boatdumb

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Oct 29, 2003
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Re: '77 70 hp Johnson sensor wires

ob thanks for your reply, I'm not sure if they are for the heat sensor or not. I just bought the boat and i'm trying to get it running but i'm not getting a spark. the sensor wires are comming into the power pack.
 

ob

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Re: '77 70 hp Johnson sensor wires

Nope not overheat sensors.Best advice I can give you is to get a motor specific manual and trouble shoot the ignition components one at a time.You'll first have to make sure that your stator is delivering the specified voltage and go from there.
 

boatdumb

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Oct 29, 2003
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Re: '77 70 hp Johnson sensor wires

how can i test the stator to see if it is doing it's job?<br /><br />this is my first boat (maybe i should have bought one that ran ha ha).
 

ob

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Re: '77 70 hp Johnson sensor wires

You'll need some specific test equipment that may be out of the scope of the general hobbyist.Multi-meter,peak reading volt meter.Charge coil volts should read around 150V a/c asssuming that the battery is fully charged and cranking engine strong.Ohm reading on the charge coil should be in the neighborhood of 450-600.Might be just as easy to swing it by a reputable shop and have the no-spark problem diagnosed and go from there.You can look for obvious symptoms of stator meltdown by checking for any sticky or gooey stuff under the flywheel and perform a general visual on the ignition coils for swelling or cracks in the cases.
 

boatdumb

Cadet
Joined
Oct 29, 2003
Messages
19
Re: '77 70 hp Johnson sensor wires

ob,<br />thanks for your help. I wanted to fix the problem on my own but i guess that is out of the picture without the proper equip. <br /><br />Thanks,<br /><br />boatdumb
 

OBJ

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Joined
Dec 27, 2002
Messages
10,161
Re: '77 70 hp Johnson sensor wires

boatdumb....don't give up on the engine. Get a service manual and learn all ya' can. May get ya' off the water someday.
 
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