1979 Mercury 20 Idle screw

[Weiss Man]

Hi Guy's

I recently purchaser a jon boat with a 1979 merc 20 and I have a general question then a diagnostic question.

General question;
The stearing arm has an idle screw on the end of it, and I would like to know how to set it. Any tips or tricks? I have been starting with an initial setting of 3/4 to 1 turn open.

Diagnostic question;
I took the boat out yesterday and after a bit of work getting it started, I took off and was running WOT with no issues. Slowed down and reversed course and accelerated, at which point she cavitated. I backed off the throttle and when I went to accelerate again the motor bogged down and died. So now whenever I try to accelerate it will die. At times it seems like she will take off but won't. I can idle in gear and that's about it.

Any thoughts?

Thanks,

Weiss Man

 

[Weiss Man]

Re: 1979 Mercury 20 Idle screw

Perhaps a little more info might help.
The motor will idle in neutral and in gear but dies when I try to accelerate. What would cause it to die under load?
Regarding the idle screw, it is the thumb screw on the end of the stearing arm. When I turn it, nothing changes unless I close it all the way, at which point it will kill the motor.

Does this help?

Weiss Man

 

[Laddies]

Re: 1979 Mercury 20 Idle screw

That is not a idle screw it's a friction screw to set the throttle, either the idle mixture is lean or the carb is dirty