6hp Johnson not running right at full throttle

[tous0024]

Had my 1965 Johnson 6hp out today and it runs great at full throttle for about 45 seconds and then it cuts down to about 2/3 throttle and stays there. Other than that the motor runs great... starts first pull idols great, no misses either. I was told to look at the coils. We pulled it apart and they look fine, but not sure if you can always tell by looking. The picture that was provided in the last thread showed them cracked and in rough shape. Our did not look like that.

Obviously we don't want to start replacing part after part until we are in deeper than we paid for the motor initially. If anyone could offer any suggestions it would be greatly appreciated.

 

[Nighthawk]

Re: 6hp Johnson not running right at full throttle

Have you torn down the carb and cleaned it ?

 

[tous0024]

Re: 6hp Johnson not running right at full throttle

I sprayed it well with some carb cleaner, but tearing down the carb is probably something I would be a little nervous about doing. I bought the motor last summer and it ran tip top for about the first month I had it and then this started happening. It was well maintained/cared for before I bought it and the motor looks very clean. Not sure what to do.

 

[tashasdaddy]

Re: 6hp Johnson not running right at full throttle

that is one simple carb, also could be a failing fuel pump, or the vent in the gas tank is not open, or clogged. also could be an air leak in the fuel line. run it without the cover, and see if that helps, could be exhaust gases coming up for a bad seal. they don't like to breathe dirty air. let us know what you find.

 

[tous0024]

Re: 6hp Johnson not running right at full throttle

Already ran it without the cover. Also tried pumping the primer while driving. Neither made any difference. I am going to rip it apart again this afternoon and take a better look at the coils and also the carb. I will keep everyone posted. Don't want to pay $300 to have it fixed when I paid $400.00 for the motor initially... but I want to fish!