Kommander Briggs Backfiring

[gstanfield]

I recently purchased a zg124e 2013 kommander. I mow about 10 yards a week and used this mower for the first time yesterday. It was in the mid90s by noon yesterday. The mower mowed great and starts right up. The problem I'm having is that when I finished a yard and shut the pto off, the engine would pop a few times like a backfire and then I would load it onto my trailer. When i would idle it down it would pop a few more times. This was only after doing a full yard. Just a quick startup and test drive it would not do it. Just looking for some insight on this.
Thanks, Garrett

 

[CCWKen]

Might be overheating or the float level is set too high. I have the 22hp version in a Sears GT5000 lawn tractor and had trouble with the engine from day one. The plastic intake manifold warped and leaked air, rocker arm came loose and constant sticking of the carb solenoid valve. It's got about 75 hours on the meter and it just sits rotting away since I rebuilt the Woods ZTR three years ago.

 

[gstanfield]

Thanks. I decided to take it into the dealer this morning. They are going to take a look and give me a call. Hoping it is something minor and I get back at it because I love the mower. Plenty of power and cuts great

 

[timswi]

On recent small engines, you have to leave at least 1/2 throttle when shutting down (gas motors) or they will backfire if you power them down to low idle when shutting down...Been going on for at least 10 years. Told it was something with emissions. My Cub Cadet did it years ago and my ZD724 will do it if I power down to idle then shut off.

 

[6Mickey]

Backfire is a misnomer! What you have described is a muffler explosion. When the ignition is turned off to stop the equipment, the momentum of the flywheel continues to 'spin down' and the fuel is still being passed through the combustion chamber and into the muffler. The vapors are unburned. When the crank shaft stops, the pumping stops, and in a short time the oxygen rich air flows into the muffler (backwards) and with the heat of the carbon in the muffler and the unburned gas vapor, bang! The explosion happens.

On the other hand, when a true backfire takes place, it is usually a timing issue where the fuel vapor going into the combustion chamber ignites in the intake and carb and bang, the explosion takes place in the intake, or it 'fires back' from the engine!

 

[CCWKen]

The Briggs has a solenoid valve or "anti-backfire valve" on the carb. That's the part that was always sticking for me. It's closes the main fuel channel so no gas flows when the key is turned off. It opens when the key is turned on. I think Garrett's problem is different and it's backfiring while running. At least that's what I gathered from his description.