2001 merc 3.0 idle mixture @5 turns out?

[mainejohn]

Finally get my new to me boat out for the made voyage. It's a 2001 merc 3.0 and has been rough running at low rpm but fine at WOT. I just got a carb rebuild kit and removed the carb and noticed the Idle Mixture screw is at 5 turns out! !!! What would cause this issue to have it that backed out? Please help

 

[stonyloam]

I don't know why it was backed out that far, but it sure could be the cause of rough running at idle.

 

[mainejohn]

Anyone know what would cause it to be backed that far out for it to stay running?

 

[stonyloam]

If you turn it all the way in, then back out about 1 1/2 turns and it will not run, then the idle circuit probably needs to be cleaned. Does it make any difference when you turn the screw in or out? If you are out 5 turns then you should be completely off the seat. Take the needle all the way out and look at the end, to see if it is in good shape.

 

[mainejohn]

I have not run it yet since I pulled the carb off to do a rebuild on it. I cleaned everything and put the kit in by the specs, only thing that seemed way off was the float was way out of spec. I

 

[mainejohn]

Update:: got it all back together at factory specs and hooked it up to ear muffs to make sure it ran. To hot today to test drive it but it did start right up and rev pretty decent. It was idling at 1100 rpm's , so I backed it down to 800 and seem good there. It would not saying running at 700, was really rough and would stall. If the motor was up to 150 temp, would the choke be shut off by then?

 

[Fishermark]

...If the motor was up to 150 temp, would the choke be shut off by then?

The only way to tell is to look. Yes, it SHOULD be off by then, but it may not be. You will have to look and see. Do you have an electric choke?

 

[NHGuy]

When the choke goes vertical it is open.ie. off.
Do this, while it's running at 800 turn in the mix screw til it starts to stumble, then turn it out a little til it gets smooth.
Then lower the idle and adjust the mix til you get the right idle speed without a stumble.

 

[mainejohn]

Should I do this while it's in gear at idle in the water or do it in neutral on muffs?

 

[stonyloam]

In neutral, on the muffs should be fine. Not a good idea to put it in gear while it is running out of the water, safety hazard, too easy to get the hose or yourself into the spinning prop. You want to hit 650-700 RPM.

 

[mainejohn]

Is it important to disconnect the throttle cable when adjustin the idle and mixture screw?

 

[bruceb58]

Should I do this while it's in gear at idle in the water or do it in neutral on muffs?

In gear on the water is best.

 

[mainejohn]

Do I need to disconnect the throttle cable to adjust the idle & air screw?

 

[Bondo]

Nope,...

 

[mainejohn]

UPDATE:: I took the boat out and had my daughter drive it while was adjusting the idle and air mixture screw and got it perfect. idle in gear is at 750 and idle in neutreal is at 800. Boat runs great and has no dead spots for bogging. When I rebuilt it I did noice the float was way out of spec and someone had the spring loaded needle seat installed. I put the solid needle in and adjusted the float along with rebuild kit and it did the trick

 

[Bondo]

UPDATE:: I took the boat out and had my daughter drive it while was adjusting the idle and air mixture screw and got it perfect. idle in gear is at 750 and idle in neutreal is at 800.

Ayuh,.... Thank you for the update John,....

If ya can get the idle down another 100 rpms, yer drive will love ya alittle more,....