96 johnson 15hp will not run at high rpm

[jctator]

I have a 96good johnson 15hp. It idles good, runs good at low speed, but surges when I try to run full throttle. I cleaned the carburetor and replaced spark plugs. Didn't help. I need some advice on what to look at. Thanks.

 

[jerryjerry05]

Re: 96 johnson 15hp will not run at high rpm

Dirty high speed jet?
Bad fuel pump diaphram?

 

[jctator]

Re: 96 johnson 15hp will not run at high rpm

Well the last time I ran it I squeezed the primer bulb while it was running and it didn't help at all. So I figured it wasn't the pump. Ill check the carb again a little better. I've heard alot of people tell me to run seafoam through it, but I also heard that could hurt the motor.

 

[AlTn]

Re: 96 johnson 15hp will not run at high rpm

seafoam won't hurt the motor, but probably won't cure your problem with high speed surging either. That orfice plug < jet > needs to be removed and cleaned spotless. Surging at high speed can often be caused by air leaks somewhere in the fuel system...cracked hoses, loose or ill fitting connections, etc.