1972 Johnson Looper 50

[mrwoodboat]

Hi- I have a '72 50 hp Johnson that was running like a top until I moved it to another boat, Now it will only crank and run when it feels like it..basically some times I can go to start the motor and it will just spin with out getting any spark to the plugs, at other times, it will crank up and run with out a hitch until it is shut down, then, well, the lottery is a better bet...my gut feeling it that the actual ignition switch is at fault. I can not imagine it being the stattor as it charges well and runs perfect when it will run. Any advice is much appreciated, also where can I find a new switch- I cannot find one listed under Sierra..Thanks all

 

[Walker]

Re: 1972 Johnson Looper 50

If you suspect the ignition switch then unplug the big red cannon plug where all the wiring goes to the motor. Jump start the engine at the starter solenoid. This will isolate the motor from the switch. If it starts and runs each and every time then your problem is somewhere in the control wiring, provbably the switch.<br />Be aware that if the motor starts you will have to kill it by choking, pulling sparkplug wires or plugging the plug back together.

 

[Texasmark]

Re: 1972 Johnson Looper 50

Or disconnecting the fuel line.

 

[Texasmark]

Re: 1972 Johnson Looper 50

Walker,<br /><br />Something just hit me. If you disconnect the red Cannon plug how do you get power to the ignition system? Or does the ignition power come in some other way; or is it supplied internally?<br /><br />I guess if the 50 has a magneto ignition that explains it; don't need it. But is the '72 50 a magneto ignition motor?<br /><br />Normally the RUN-START switch supplies power and if this is like Merc's when you disconnect the connector you would have disconnected the input voltage to the ignition system.<br /><br />Mark

 

[mrwoodboat]

Re: 1972 Johnson Looper 50

Ok- I have taken the cannon plug apart- still won't start- tried running 24 volts to the starter to speed up the rpm while cranking- no luck...I am puzzled...it has not started the last 20 or so times I have tried- tomorrow it may start the first time I spin the motor, who knows... Yes it is getting good fuel delivery..<br />thank you guys