Runs, but stutters/mini backfires/misses. don't know what to call it.

[Marty13]

short version of the story... lol Mower ran great till back at the beginning of the summer. 2nd time I used it, it died after driving from shed to house, maybe 100 ft and would not turn over after that. Could not even spin the motor by hand. Parked it did some research here and there (been having some health issues this year) and a couple weeks later, was able to determine it may be hydrolocked after discussing with a friend. Came home, tested and confirmed this theory quickly by draining the "oil". which was also full of fuel. Turns out the solenoid on the float bowl that is supposed to shut off the flow of fuel when the key is off, had gone bad and the entire tank of gas I had just filled prior to it quitting on me was inside the engine. not sure why it initially ran for the minute or so before it died, this part throws me off still, however after draining engine and refilling with oil, I was able to get it running again. since then, though it's got a sputter/miss/mini backfire. I'm not really sure how to refer to it, but it otherwise runs fine. just wondering if anyone has ideas as to what the issue may be. I have pulled the carb and cleaned it thoroughly. i even bought a replacement (not O.E. though) and it turned out to be worse than the original so i put the original back on. did a valve adjustment on it, float bowl has been replaced as well and I added an inline fuel shutoff to prevent the hydrolock situation again. I'll replace the solenoid once i determine if this issue can be resolved and if i want to put any more $ into this 20 year old mower or if it's just time for a new one. I'm going to try and upload a video of how it sounds. it is a bit difficult to hear, but if you listen closely, you can definitely hear the miss/backfire/whatever you want to call it. Any ideas are most welcome! just stumped as it runs just as well as it did before this issue occurred, with the exception of the miss, I'm just worried about the long term effects of running it this way and would like to get it figured out. Thanks in advance!

 

[bertsmobile1]

From the top.
The solenoid does not shut off the fuel supply to the carb.
It rams a plug up the end of the supply to the main jet to stop, fuel vapour entering the engine via the venturi tube.

The float valve shuts off the fuel SUPPLY to the carb.
When it does not work the bowl overfills and the raw fuel dribbles inside the engine via the bowl vent.
Once upon a time there was an overflow tube so you could see what was happening but the EPA decided it was better for the environment for the entire tank of fuel to drain into you sump then get thrown out.

A severe hydro lock tries to compress a cylinder full of liquid fuel , but liquids do not compress so it can bend the con rod, break a ring or blow the head gasket

SO run your engine for 5 minutes, shut it off then remove the dip stick .
If smoke comes out the gasket is gone.

In any case , remove the float bowl and hold the float up while cranking the engine.
No fuel should come out.
Work the float to make sure that fuel flows then stops then flows.
Old fuel lines can crumble inside or go gummy and this breaks off and get stuck in the float valve on a brand new carb.