50 Horsepower Johnson Lost Spark

[bruoff]

I left my 1985 Johnson 50 hp for about a month and have lost spark. I have the factory shop manual, but it asks for meter checks from a meter that I don't have. Can I check the CDI pack with a normal VOM. Does anyone have a place to start on this delimma? I've checked the switch and kill switch, the seem to be operating<br />correctly. Do these CDI boxes just die??

 

[Joe Reeves]

Re: 50 Horsepower Johnson Lost Spark

Bob... With the spark plugs removed, rig up some type of spark tester whereas you can set a 7/16" gap to be jumped. The gap must be 7/16".<br /><br />The spark should jump the gap with a strong blue lightning like flame..... a real strong blue snap!<br /> <br />If no spark, disconnect the RED main electrical plug at the engine (Spark plugs still removed). Crank the engine via the starter solenoid using a small jumper wire from the battery terminal on the solenoid to the small 3/8" terminal nut that energizes the solenoid (not the ground nut).<br /><br />If the spark is now okay, the usual cause is a shorted ignition switch, in which case, replace it. If still no spark, the usual cause is the powerpack.

 

[bruoff]

Re: 50 Horsepower Johnson Lost Spark

Thanks Joe, I'll try that this evening. Are you in the Tampa Bay Area?

 

[bruoff]

Re: 50 Horsepower Johnson Lost Spark

Joe, tried it and had spark. Hooked up the "muffs" and ran the motor. It ran just fine until I reconnected the red plug. It then died. I'll get a new switch early next week Thank you so much!

 

[Joe Reeves]

Re: 50 Horsepower Johnson Lost Spark

Valrico

 

[phatmanmike]

Re: 50 Horsepower Johnson Lost Spark

i had that same problem MANY times. i have since removed my key switch and use a simple toggle and a red push button switch. no more problems.

 

[bruoff]

Re: 50 Horsepower Johnson Lost Spark

Hey Joe and (everyone else), I finally got back to my repair of the 50hp Johnson. This is really strange. As reported last month the darn thing runs when the red plug is removed and dies when it is reconnected. NOW, With the control box disasembled, (ALL wires disconnected and seperated to prevent short). The darn thing still dies when the red plug is reattached!!!<br /><br />All wires show continuity and no cross shorting.<br />Is there something about the wiring harness that I don't understand? It appears to be 8 seperate wires with seperate connectors on the control end and a big red master plug on the other. Today I will use a better meter to check for shorts. I'm baffled. I usually can do circuits rather well. HELP

 

[rodbolt]

Re: 50 Horsepower Johnson Lost Spark

hello<br /> double check the emergency stop switch.<br /> with modern electronics it does not have to have a dead short just some corrosion on the inside. the kill circuit has about 240 volts on it. does not take much and it will have a current path to ground.by following joe's advice you have isolated it to the stop switc,ign switch or wire harness. we dont see many harness failures on that harness. we do see a lot of emergency stop switch failures. that engine kills by shorting the blk/yellow stripe wire to ground. remove the blk/yellow wire from the ign switch and retest

 

[bruoff]

Re: 50 Horsepower Johnson Lost Spark

Thanks RodBolt, The black/yellow as well as all other wires are removed, seperated and waving in the breeze. That's why I'm thinking harness??

 

[Stumpknocker]

Re: 50 Horsepower Johnson Lost Spark

Darned if that isn't an understatement about Florida boats!<br /><br /> I'm rewiring one now. This one isn't so terribly bad, but the last one was incredible. <br /><br />Took two of us 3 months on and off to rewire and rebuild that Bass boat.

 

[bruoff]

Re: 50 Horsepower Johnson Lost Spark

Found it The previous owner had overly shortened the main harness cable and installed a very poor splice. I cut out the splice and replaced with a terminal block encased in a plastic "Handy Box" from Radio Shack. All treated with Boshild and sealed up. I may just buy a complete harness, if I can find one at a good price. Thanks for the input! I shouda' looked for a splice first thing. Don't know about everywhere, but here in the "Sunshine State" every boat that I have owned has been really miswired by the previous owner.