25 Johnson loss of power

[Deke51]

I have a 1992 25 HP johnson that very intermittently loses power while at full throttle (mostly). I at first, in the spring, suspected water in the gas but this was not the case. All filters are clean. At high speed the motor will very suddenly power back a good 50 to 75% but never stall completely, and resumes power very quickly on its own. This may happen once or maybe 2 or 3 times in quick succession. The carb has been cleaned and a new power pack put in. I have tried 3 gas tanks and 2 hoses and it happens with all of them. The motor may run beautifully for 2 days then all of a sudden power back. I suspect a fuel problem but my mechanic keeps insisting it cant be the fuel pump as he has never replaced a fuel pump on these motors. The motor has loads of power and idles beautifully without powering back.

 

[lyncraft_mechanic]

Re: 25 Johnson loss of power

have you tried pumping the fuel line bulb when you loose power? by doing this it will by pass your fuel pump and the motor should return to full power!
have you tested the compression or the spark? you could be loosing a cylinder due to a bad coil!!

 

[tashasdaddy]

Re: 25 Johnson loss of power

check for corrosion on all electrical connections.

 

[Deke51]

Re: 25 Johnson loss of power

Yes, I have pumped the fuel bulb, actually ran the motor with the bulb in my hand. But the problem is so intermittent I could hold the bulb all day. I am 99% sure the bulb is soft when the motor backs off, but it always recovers quickly on its own. I know the spark is good as my mechanic tested that and compression should be good based on the power and ease of starting.......if a coil is failing briefly is there any way to check. i do trust my mechanic but hes stumped. He came to my camp one day to run the motor and it ran beautifully.