1971 Johnson 100 hp with fuel problem

[keith brown]

I have had 1971 100 hp motor. It will start and accelerate well but with 30 secs to 1 minute it will lose power by 80%. It is as if it is not getting enough fuel. It will still run but at very low rpms, with the throttle wide open.
I have changed the fuel pump, primer bulb, bypassed the fuel tank and gas line to the motor with a portable one. Any thoughts? I also tightened two gas lines after the fuel pump. It is diffuclut to get to the other lines. Any ideas?

 

[keith brown]

Also, the motor is not smoking, I have not checked compression or changed spark plugs since it runs great for 30-60 seconds. The lower units oil was replaced with proper oil. At higher rpms water comes out of the exhaust. I do not see water out of the exhaust when it is at idle.

 

[Boobie]

Take the cover off of the carbs, get some premix fuel in a squirt can and shoot it into the carb throats when this happens. If it picks up and goes your got dirty carb probs.