backfire on shutdown

My Gilson garden tractor with a Briggs engine series #320400 horizontal drive has a light backfire when engine is completely shut down.
Any suggestions?
Thanks, Fred
 
Backfire out the exhaust?

Is there a solenoid valve on the bottom of the carb? It may not be closing. Try disconnecting the wire with the engine running, it should kill the engine. If not the valve is not closing, letting unburned fuel in the exhaust while the engine is coasting down.

If there is no valve on the carb, try idling the engine down before shutting it off.
 
(quoted from post at 23:03:05 05/16/14) Backfire out the exhaust?

Is there a solenoid valve on the bottom of the carb? It may not be closing. Try disconnecting the wire with the engine running, it should kill the engine. If not the valve is not closing, letting unburned fuel in the exhaust while the engine is coasting down.

If there is no valve on the carb, try idling the engine down before shutting it off.

No solenoid valve.

It lightly backfires thru the exhaust. I do let it idle before shut down.

Will try disconnecting the wire.

Thanks Fred
 
Try letting the engine idle before shutting down the engine. I have a 1971 14hp Wards made by Gilson. I wouldn't use the choke as this may wash
your cylinder of oil. I plowed my garden this Spring and so far I've never had it backfire. Hal
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With no fuel sol on carb & given the age of eng/tractor the most likely cause of problem is carbon buildup in head,around/on valves & in muffler where unburned gas vapor is ignited by hot carbon deposits after eng stops,you may have to remove head & clean head,block under head & possibly replace muffler or live with it as is.
 
Well here is something I can add. Like others have told you, idle it down is always good. I would add that you switch to Hi-test gas and summer fuel with some Star-tron in it. Winter fuel evaporates like crazy. You are getting post ignition. A lot of posts say carbon, and there is an old mechanics solution. Take off the air cleaner and start up the engine. Get it good and hot and have it running pretty fast. NOW take a squirt can and fill it with water. Squirt a little at a time so that you almost kill the engine but not quite. It will remove any loose carbon and if you keep at it even more. The steam will scrub the carbon out. If you want to pull the head then you can wire brush everything clean. For giggles try the water! Jeffcat
 
on the cub cadet forum they say idle it down and as you turn the key off push the throttle wide open. it does work. bill
 
Thanks to all that responded, you are great Americans wanting to help. At 89 years haven't been able to get at it.
Our worthless congress allowing ethanol to be in gasoline is damaging all small engines and may be the problem. Not sure what Star-tron but will check it out.
Again thanks, Fred
 

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