Idle screw so tight choke can't shut but mercruiser idles fine once started.

[egleas84]

This is an '83 2.5L Merc 120

My carb appears to have adjusted itself this week. It still idles 600-800 RPM's but I recently had issues starting it because the choke flap didnt set when i pumped to WOT. I loosened the screw and the flap was able to shut but haven't attempted a test fire yet to adjust the idle, thought I'd ask for advice here first.

So my problem is if i loosen the idle screw wont the boat idle much much higher, dangerously above 1000 RPM? Or is there something else that needs adjusting? I replaced the throttle cable a month ago but until now I've had no issues.

Idea's?

 

[thumpar]

Re: Idle screw so tight choke can't shut but mercruiser idles fine once started.

When you loosen the screw it should lower the idle. On my 83 that I just rebuild the carb on the screw is about mid-point. Mine is a Rochester so maybe you have something else.

 

[egleas84]

Re: Idle screw so tight choke can't shut but mercruiser idles fine once started.

I too have the Rochester. If i adjust the throttle cable would that influence the idle so i can have move the idle screw back so the flap operates normally?

 

[04fxdwgi]

Re: Idle screw so tight choke can't shut but mercruiser idles fine once started.

This is an '83 2.5L Merc 120

My carb appears to have adjusted itself this week. It still idles 600-800 RPM's but I recently had issues starting it because the choke flap didnt set when i pumped to WOT. I loosened the screw and the flap was able to shut but haven't attempted a test fire yet to adjust the idle, thought I'd ask for advice here first.

So my problem is if i loosen the idle screw wont the boat idle much much higher, dangerously above 1000 RPM? Or is there something else that needs adjusting? I replaced the throttle cable a month ago but until now I've had no issues.

Idea's?

Something doesn't sound right...... I would check real close to see if something didn't fall off or get jammed into the linkage on the carb. Carbs don't "self adjust" the linkage. Never have / never will........ When an adjustment moves "by itself", 99.9% of the time makes things much worse. Someone had to physically turn that screw in if it idles correctly. Was anyone monkeying around / tweeking screws on the carb? Has it just recently been serviced by "others"? Has the carb been changed recently?

Way too many questions for this one.

 

[egleas84]

Re: Idle screw so tight choke can't shut but mercruiser idles fine once started.

I ended up adjusting the throttle cable and the idle screw in different variations and got it settled half way and it seems to work fine now. weird.