Johnson loosing power idling rough??

[gitterdunn]

My 1994 Johnson 40 hp outboard starts running fine but after 20-30 mins. at higher rpm's, It looses about 75% of power then starts to idle rough and stalling. When it cools it will usually run better for a while. I have taken it to a mechanic about 4 times. He has redone carbs, but everytime he has it it runs fine in his test tank, (which he uses at lower rpm's). Could this be an ignition problem? This thing is driving me CRAZY!!

 

[TimmyC]

Re: Johnson loosing power idling rough??

Good luck been going thru some problems like that with my 150

 

[ryanmitton]

Re: Johnson loosing power idling rough??

I get a similar thing on my 20 hp johnson and my solution is to pull out the choke stick and it works fine.

 

[tashasdaddy]

Re: Johnson loosing power idling rough??

the first thing is would do when it starts acting up, is check spark, you could easily have a coil that is getting warm, and failing. also put your hand on top of the block if you can hold your fingers there for a 3 count the motor is not running hot.

ryanmitton, if you are having to do that, you have a fuel starvation problem.