Johnson 50 cuts out

[RKeller]

I just purchased a boat with a '73 Johnson 50hp. the boat hasen't been run in years. I took it out for a spin and it ran great for about 15 miles full throttle. I turned around to head back up the lake and when I went to give it full throttle it had no power. I switched to a different tank and still no power. after driving at full throttle and barely moving for about 10 min. it kicked back in and ran like a champ. Seems like it was running on one cylinder. any ideas?

 

[tashasdaddy]

Re: Johnson 50 cuts out

seach 'awakening a sleeping outboard' use the red search function at the top of the page. do this before you ruin that motor. i had a '73 50 evuinrude, same motor. after sitting up the carbs, water pump, need to be cleaned and rebuilt. you may have a bad coil or coils, or even a bad power pack. welcome to iboats.

 

[RKeller]

Re: Johnson 50 cuts out

thank you, I was thinking maybe a coil was bad. I'll take a look at that post.

 

[tashasdaddy]

Re: Johnson 50 cuts out

using muffs, start the engine, with insulated pliers remove one spark plug wire, idle should drop a little. if engine dies replace wire restart, remove other wire. engine will run on one cylinder. if it continues to run on one clylinder. do this. disconnect battery, swap coils with each other( don't just swap the wires) if the problem follows the coil you know which to replace. i prefer to replace both at the same time. also check your compression

 

[RKeller]

Re: Johnson 50 cuts out

sounds like a plan. I'll give it a try. I was thinking I should replace them both.

 

[RKeller]

Re: Johnson 50 cuts out

well, if I remove the top plug wire the motor keeps running but not as well. if I remove the bottom wire the motor dies. I swapped coils and the issue did not follow the coil. checked compression both are around 125. after running for a few minutes when I remove the plugs the top plug is clean and wet and the bottom plug is blackish and wet. when it's running it is not smooth, seems to be running on 1.5 cylinders. next step carb re-build? is there a way to check the power pack? <br />how should the lean rich knob be used(set)? I removed the air box in front of the carbs and the linkage was detached from the top carb, the one that seems to be acting up.<br />thank you for your help!