honda mower spitting gas

Hi everyone,
I have a honda hrx2172vka that I bought several years ago.
This problem I have, and it just started , is when I start the mower, gas will spit out the exhaust and the engine will putter for awhile and then run smooth.

I bought a grass trimmer at the same place I bought the mower last week and the salesman said that I should mix Star Tron enzyme fuel treatment in with the gas because of the ethonal in the gas.

It seems the problem with the mower started to act up after I added this to the fuel.
Also when I started the mower tonight, it did not want to start and when it finally did it ran low idle and rough untill I took the air cleaner off and noticed fuel was in the air cleaner. Then it started running smooth.

I would appreciate any help in knowing what the problem could be .

Thanks, Jim

sounds like its running too rich like its flooding when the engines off. try a needle and seat

If you normally leave fuel in the carburetor over the winter, you could have varnish build-up in the bowl. Sometimes the varnish can get between the needle and seat which can cause it to flood.

If there is any water in your fuel, the startron will cause the water to be suspended in the fuel with the eithanol, which may be part of the spitting problem. the startron also contains carb cleaning agents which could be breaking stuff loose causing leaking problems with the needle valve in the carb.

Thanks guys.
It occured to me that I wasn't turning off the fuel after I was done using it.
But I haven't been doing that for a few years now.
I turned the fuel off and started it to burn off the fuel in the carb. and tried starting it the next day and started right up. I'll have to wait untill I cut the grass to see if turning off the fuel helps.
And it just might be the fuel treatment cleaning it out.
Thanks again.