We'll try the easy way first. This way you won't have to mess with governor linkages and rpm settings.
Okay, here is what you do. You will need a spray can of carb cleaner. When using carburetor cleaner remember to ALWAYS wear safety glasses. Cleaner in the eye can be very painful at best and life threatening (Yes, LIFE THREATENING) at the worst.!! (And using spray cleaner it is very easy to have spray back into your eyes).
Remove the spark plug. Remove the air filter and the air filter housing (should be two screws attaching it to the carb throat).
Use some small vise grips or something to pinch off the fuel supply from the tank and then remove the bolt from the bottom of the carburetor bowl. Carefully remove the bowl from the carb body being careful not to knock or damage the plastic float. Let the float gently drop down and hang from its hinge.
Carefully remove the rubber o-ring which seals the edge of the carb bowl. Check it for cracks. Take a look in the bottom of the carb bowl. If there is any green sludge or any deposit, spray it with carb cleaner and rub it away with a rag.
Now, using the "straw" attachment which should have come with your carb cleaner can, spray cleaner up the centre tube in the carb body. Spray the cleaner up under the rest of the carb body. Follow this with a GENTLE blast of compressed air if you have it, to dry the cleaner up. Hold the float gently while you are using the air so that you don't damage the hinge of the float or blow the needle inlet valve away.
Look down the throat of the carb from the spot where the air filter housing attaches to the carb. You should be able to see 2 or 3 small holes facing you. Again, using the straw attachment, spray the cleaner into each of these holes. Put the straw right up to or into the holes. Spray into these holes and you should see the cleaner start to drip out from underneath the body of the carb where the float is attached. When you see the cleaner start to drip out then you know these passages are open. Follow this with a gentle blast of air.
Now carefully replace the o-ring around the carb body which seals the carb bowl. Make sure it is not twisted or kinked. Being careful of the float, replace the bowl onto the carb and re-attach the bolt to hold it on. Spray a little bit of cleaner down the carb throat around the throttle butterfly which is at the other end of the carburetor. Make sure the butterfly valve is moving freely.
Take a good look at the gasket between the air filter housing and the carb body. This particular gasket is very easy to tear. Make sure the primer hole is unobstructed by the gasket and that it will line up correctly with the hole in the carburetor. If there is any question about the gasket, replace it. A new one will be a couple of bucks.
Re-attach your air filter housing and air filter. Make sure the air filter is clean or new. Re-install your spark plug. Add fresh from the gas station fuel. Do not use boat gas or marked farm gas in your small engines. Check the oil level is correct. Prime the motor and then pull it over. Now what happens? Has that fixed the problem?
Please let me know how it goes. If that doesn't solve the problem then we can re-assess your situation. If it has solved the problem for you, please click on the green Accept button. Good luck.