How To Adjust The Carburetor On A 40 Hp Mercury 2 Stroke Outboard?

How do you adjust the idle on a 40 hp Mercury outboard?

Remove the motor housing cover from the top of your Mercury motor. Start your Mercury 40 horsepower motor and allow it to idle. Insert a screwdriver into the Mercury’s idle adjustment screw, located at the bottom of the carburetor, and turn it to the left until the motor barely continues to run.

How do you adjust the fuel mixture screw on an outboard motor?

Adjust the idle stop screw on the side of the carburetor near the choke cable, turning the screw with a screwdriver until the vacuum gauge is reading about 600 rpm. Turn the idle mixture screw counterclockwise 1/4-turn at a time until you hear the engine begin to stall out, and turn it clockwise 1/4-turn.

How do you adjust the idle on a 35 hp Mercury outboard?

Tighten the cam-follower screw and turn the idle-speed screw inward until there is a gap of 0.005 inches to 0.04 inches between the cam and the cam follower. Start the motor and allow it to idle until it reaches its normal operating temperature.

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How do you adjust the idle on a Mercury outboard 90hp?

In the water in forward gear slowly turn it in until the engine coughs and back out for a smooth idle. Do that several times on all the carbs turning 1/8 turn at a time and wait 20 seconds between adjustments.

How do you lean out a carb at idle?

The first thing to do is not set up the idle speed, but to set the Idle mixture screw to lean best idle setting. First, turn in the mixture screw until the engine dies or runs worse, then back out the screw (recommend turning ¼ to ½ turn at a time). The engine should pick up speed and begin to smooth out.

How do you adjust a idle screw?

Adjust idle mixture by turning idle mixture screw slowly clockwise until the engine runs poorly. Note position. Slowly turn the screw counter-clockwise until it starts to stumble.

How do you adjust a carburetor on an outboard motor?

The idle adjustment is on the underside of an outboard carburetor. Use a small adjustable wrench or screwdriver and rotate the idle adjustment 1/4 turn clockwise until the engine idle slows. Rotate the valve counterclockwise in 1/8-turn increments until the engine idles smoothly.

Where is the idle screw on a carburetor?

The idle mixture screw controls the air fuel mixture at idle speed, and often is located near the throttle plate.

Why does my boat stall in idle?

Designed to regulate the engine idle speed, a malfunctioning idle air control valve can cause the engine to stall. The inside of the fuel hose is susceptible to deterioration. If left unchecked, it can cause stalling and in extreme cases engine failure.

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Why does my outboard idle high?

High idle normally indicates it is getting extra air or fuel, not from the carb. This can indicate a vacuum leak.

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