B&S detonation?

[GimmeTorq]

Don't know if that is the right word to describe it but the B&S OHV engine in my Craftsman LT1000 lawn tractor, randomly surprises me with a loud "bang" when I shut it off... I use unleaded regular (89) gas with Seafoam (about 1-1.5 oz per gallon) as a stabilizer. Any idea what could be causing this? Could it be the Seafoam? Maybe carbon deposits?

Thanks

 

[80caprice]

Does it have a little solenoid on the bottom of the carb? Let it idle for a few seconds before you cut it off.

 

[JAYCEE]

I have an LT1000. By idling the engine before turning it off should fix this problem.

 

[GimmeTorq]

Not sure if it has a solenoid... Need to check.

So it is not necessarily a problem with the engine but possibly "normal" behavior then? I'll give your advice a try... It is kind of embarrasing when the neighbors are out in their yard and this happens...

Thanks guys.

 

[UncleS2]

When my mower does that, it's because the air filter is much too dirty & is choking down the carburetor. How clean/dirty is your air filter? Worth a look?

 

[80caprice]

Reason why I asked about the solenoid, its what they call a anti-backfire solenoid, shuts the fuel off immediatly when you shut the engine off, so that little bit of fuel won't go flying into the hot combustion chamber (hence idling it for around 30 seconds to cool it down) I got the same thing when I was in a hurry, and didn't shut my riding mower off via the key switch, I just got off it and let the seat switch kill it.... and it POPPED because the solenoid didn't shut the fuel off. Doesn't seem to happen much with side valves, more with ohv engines.

 

[GimmeTorq]

80caprice,

Just checked it... It has the solenoid. I always try to use the key switch to shut it off but maybe I should let is idle for several seconds before I do so.

SH, also checked the air filter and the pre-cleaner. They look good. Thanks for the suggestion though.

Thanks again guys.

 

[Arctic388]

i had this problem once where the mower would stay running. a mouse had a nest inside the cover beside the flywheel. it would only die if i idled it all the way down and still had blade engaged and still in gear goin up hill and turn switch off. it was that hot. other than that the gas could be the culprit. old gas can cause it.

 

[GimmeTorq]

Well, waiting 4 to 5 secs idling before shutting it down worked for that scenario, but I did get it once when starting it up. Scared the crap out of me!

I guess that if the solenoid was bad, it would happen more frequently. I wonder if it is the gas. I think this might have been gas which I bought during the winter months for my snowthrower.