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J.R., Small Engine Technician
Category: Small Engine
Satisfied Customers: 7445
Experience:  Owner of outdoor power equipment business, repairing all makes and models.
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How do I keep my lawnmower from flooding When I put gas in

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How do I keep my lawnmower from flooding? When I put gas in the tank, it simply runs out of the air filter.

Hello and welcome to Just Answer,

Replace the needle valve and seat in the carburetor.

Customer: replied 6 years ago.
The needle valve looks fine. What is the "seat"? Does the needle valve wear?
The needle valves do wear. The seat is what the valve seals against. Replace them as a set.
Customer: replied 6 years ago.
The seat may actually be missing. (I got the lawnmower in this condition) Is this like a rubber grommet or something that is in the "guideway" where the needle goes? Or is this the "spring like" wire that holds the needle valve against the float?

What make and model of engine is it?

Customer: replied 6 years ago.

Sears 3.5 HP ModelNNN-NN-NNNN/p>


I was able to "trick it" into starting and actually mowed until the gas ran out. After I added more gas it ran out the filter.

Replace the needle valve and seat. See attached link

Customer: replied 6 years ago.

Sorry for the delay, these were the pictures I was looking for.

I am assuming the INLET needle valve (please continue below), and there is a "seat" inside the carburator that must be worn.


The bowl "nut" on my engine also has a needle that screws from the bottom of the nut into the bowl nut. It has a spring as a "tensioner" I think. The nut does have the 4 holes that the link showed. What would be a good "starting position" for this?

Replace the needle valve and seat. They are all the same. I just used that link to show the valve and seat.
J.R. and other Small Engine Specialists are ready to help you
Customer: replied 6 years ago.

I appreciate the time you have spent in trying to help me. I asked additional questions that you didn't answer. I have also (after two attempts) to locate a valve and seat......did you know they only sell in complete sets, so i have to spend money on parts i won't use.


i am going to attempt to reassemble with the new seat. Answer my other question (previously posted) and let me see if this works.


You've earned your money, but i have not been completely "sold" on the process.



The needle valve and seat can be purchased separately. Here is a link to the needle valve and seat.

What did I not answer for you?

Customer: replied 5 years ago.
See my previous response as to my overall satisfaction with the web site. The new valve and seat DID NOT repair my problem. The additional questions I asked on the same subject (so that I would be successful) would have helped....I believe. AS SAID, much time was spent on my issue....but the solution was not "quick", still did not resolve it. However, he earned his time
The needle valve and seat are what control the fuel entering the carburetor. If the engine is still flooding then check the float for having a hole in it.