Carburator needle valve not letting gas to engine

Yes it is the needle valve that is leaking or If you had this happen after a rebuild kit was installed then you have the float set to high.

The floater of the carburator is bad(Needle). its leaking gas at the carburator and the gas is coming inside the engine at piston intake valves.
Replace carburator needle that stops the intake of gas at the Carburator.

This happens when the gas needle valve in the carburator sticks open. With it open, gas continues to flow into the carburator then into the cylinder and finally down into the crankcase. It can be caused by dirt in the needle valve's seat, a stuck needle or float. Most of the time you can remove the float bowl and flush out any dirt. If there's a lot you should consider flushing the gas tank and check your gas can for dirt. If the washer has been sitting for a long time the problem could be varnish is gumming up the carb works. Carb cleaner works well to flush that out. If the float, needle or seat is damaged you'll have to rebuild or replace the carb.

If hose coming off carburator does not connect to anything then it is the over flow for carburator when float gets stuck and does not close needle valve causing excess fuel in carburator bowl and is drained automatically through vent orfice connected to hose that gas is dripping from. If this is the case then remove carburator bowl, check float, needle valve and o-ring in where needle valve goes. sometimes when carburators sit over winter with gas in them the gas breaks down and over time will gel/harden and cause float to hang up and o-ring for needle valve to deteriate and not sealing properly. clean and replace parts as nessesary.
I hope this helped.

The needle and seat in the carburator need to be replaced . Gas continously flowing is a stuck float which operates the needle valve in the carb.

You have a problem with your carburator.The problem is most likely the float, the needle valve ,or the needle valve seat. This isn't a difficult fix, you need to remove the fuel bowl under the carburator which is held in place buy a 1/2 inch bolt. There you will see your float, gently push up the float, it should be parallel with the upper section of the carburator. If not adjust float to make this happen. If float is off this is your problem, also float should not be full of gas, if so replace. If not we move on to the needle valve, remove pin that holds up your float and inspect your needle valve tip , if damaged replace. This could be your second problem,if not we move on to the third problem.The needle valve sits in a seat, it is about 1/4 inch round with a 1/32 inch hole in the center, top is flat, bottom is grooved. This seat can be removed with a pick tool. This problem can be fixed with carburator on the engine, but most of the time carburators are removed. You can do what ever you wish.
I believe the problem is with your float adjustment , you can fix this quick and get mowing again.
I am interested in how you make out. GOOD LUCK.

This is caused by a problem in the carburator, usually the needle valve is stuck open letting gas continue to flow into the motor even when the float bowl is full. Things to check for are that the float is still in tack and floats on the gas so it can close the valve. More likely there is something stuck in the needle valve holding it open. If the needle valve tip or seat is damaged it can also cause this problem.

On the top of the carburator there is a needle valve, closed by the float lever. 
If the carburator chamber is full with gas, the valve is closed and no more gas can enter the chamber.

If the chamber is empty and no gas flows inside, the valve may be stuck in closed position. Cleaning or some sharp (but not very hard) knoks on chamber cover may help.

Some times the float gets broken and falls down. This is a bigger damage, because it may lead to carburator overflow.

If you are getting fuel in the oil it can only be coming from one place. The float needle valve in the carburator is sticking open causing fuel to flow from the carburator into the combustion chamber, past the rings and into the oil. The only fix is to remove the carburator, remove the float bowl and the float. Remove the needle valve and clean the needle seat. Inspect the needle valve tip to see of it is damaged in any way. Remember while you are inspecting the needle seat that the smallest of particles can cause your problem.

I recently had the same issue with a tiller that hadn't been started in over 8 years. Turns out that old gas had left a varnish coating in the carburator keeping the gas from feeding. Rebuilt the carburator with new float, needle valves and bowl, new Welsh plug. Fresh gas and two pulls later it went to churning. Took a short time to adjust the two needle valves for idle and full throttle and we went a-tilling.