'72 65HP Johnson won't throttle up

[Chaz1]

I've got a 1972 65HP Johnson that won't throttle up without revving the motor in neutral for a few seconds first. It will run well at a slow idle speed all day long and runs well once you rev the motor in neutral for a few seconds then drop the rpm's, pop it back in gear and then punch it. It usually will take right off. I can ride around all day long at any rpm but once I drop it back to an idle rpm I have to repeat this "revving" process to get it to take off again. I figure it's probably a carb adjustment but not sure where to start. Any help is greatly appreciated. Thanks, Chuck

 

[Chaz1]

Re: '72 65HP Johnson won't throttle up

Anybody have any thoughts?

 

[Molaker]

Re: '72 65HP Johnson won't throttle up

I'm going to guess the idle is set a little low. It should idle around 600-700 RPM in forward. Usually that's around 900-1100 RPM in neutral. There is more exhaust backpressure when sitting still, placing a some load on the engine. Putting it in gear then adds to that load. Starting the boat moving reduces the backpressure. This might explain why it will idle along with no problem, yet die when you first try putting it in gear.

 

[clemsonfor]

Re: '72 65HP Johnson won't throttle up

id also say idle adjustment or linkage or a carb problem like flooding etc.

-nate