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.
How do you adjust Mercury carbs?
Turn the idle speed screw on the carburetor linkage to adjust the motor’s speed to between 700 and 800 rpm. Put the motor in “Forward.” Turn the mixture screw clockwise until the motor begins to misfire. Turn the screw counterclockwise one-quarter turn or until the motor no longer misfires.
How do you adjust air fuel mixture screws?
Turn the screw clockwise until the engine starts to sound rough.
- Tightening the screw weakens the air and fuel mixture and decreases the amount of fuel flowing to the engine.
- Tightening the screw is also called making the fuel mixture leaner, which lowers the RPMs at which the engine idles.
How do you adjust a carburetor on a boat?
Start the engine and open the carburetor to the full open position, then adjust for peak R.P.M. with the main needle as previously described above. Close the carburetor barrel slowly until the lowest possible speed is reached without the engine stopping. Go to full throttle after about 10 seconds of idling.
How do you tell if a carburetor is rich or lean?
If the insulator near the plug tip is a nice light tan colour then it’s running approximately correct at that load/rpm. If they’re white then it’s running lean, if they’re a dark brown or worse colour then it’s running rich.
Why does my outboard motor shake?
Just one loose motor mount can cause engine vibration, so you must make sure they are all tightened. … There are only three other things that could be causing it: engine misalignment, the propeller shaft or the propeller.
What are the two adjustment screws on a carburetor?
Find the adjustment screws on the front of the carburetor.
There should be two screws on the front of the carburetor, which are used to adjust the air and fuel mixture. Often these look like flat-head screws and you can use a screwdriver to turn them, adjusting the amount of fuel and air mixing in the carb.
How do you fix rich fuel mixture?
You can apply these methods described here to fix the rich mixture problem:
- Check The Air Duct’s Flap. The flap inside the air duct is an actuator that serves as choke. …
- Vacuum Lines And Hoses. …
- Clean The Mass Airflow Sensor. …
- The Oxygen Sensor. …
- Change the spark plugs.