Carb Idle Adjustment

[mjquillici]

Hello,

I have a 2002 Mercury 15 hp 4-stroke. It has very low hours on it, and has been used on and off over the last nine years. Can anybody tell me how to adjust the idle air/fuel mixture? When she's not 100% warmed up, she dies out if I try to idle her too low and stutters on acceleration from idle. Once she's been running for about 10 minutes, it's all good. I also picked up some SeaFoam, and am hoping that will help things out too.

Thanks!

 

[CharlieB]

Re: Carb Idle Adjustment

You first need a FACTORY service manual, it will spell out the carb and adjustments in detail far better than any of the aftermarket manuals.

The idle mixture screw is covered by a 'plug' that must be drilled and pulled out to gain access to the screw.

Factory idle mixture is set a bit lean as the accelerator pump provides additional fuel during throttle opening.

Then, carb cleanliness is critical, there are a few very small holes in the top of the carb throat to allow fuel flow as the throttle plate is opened, any of these plug with dirt or mineral and performance near idle is affected.

Once the carb is clean, float height checked, accelerator pump checked, and the motor fully warmed up, adjust idle mixture to best idle while IN the water and IN Forward gear.