Backfiring from full throttle to idle

kenneth2

Member
Joined
Jan 28, 2012
Threads
12
Messages
36
I have a 15 year old walker with a Kohler ech740-3031 with fuel injection. Backfires badly from full throttle to idle. I have seen discussion on shutting down at half throttle. I never had this problem before. Spark plugs a little sooty, anything I can do with Eli to make it run leaner. Spark plugs were 2 heat ranges too cold. I can try replacing first.
 

Craftsman Garage

Well-Known Member
Joined
May 2, 2021
Threads
40
Messages
512
I have a 15 year old walker with a Kohler ech740-3031 with fuel injection. Backfires badly from full throttle to idle. I have seen discussion on shutting down at half throttle. I never had this problem before. Spark plugs a little sooty, anything I can do with Eli to make it run leaner. Spark plugs were 2 heat ranges too cold. I can try replacing first.
This is usually normal to some extent because when you lower it to idle, you are blocking the air from entering, which sets the mixture uneven temporarily, and that unburnt fuel is pushed into the hot muffler where it explodes. It wouldn't backfire if you always kept it at full throttle as you should :) Idling is bad for these engines.
 

Craftsman Garage

Well-Known Member
Joined
May 2, 2021
Threads
40
Messages
512
I have a 15 year old walker with a Kohler ech740-3031 with fuel injection. Backfires badly from full throttle to idle. I have seen discussion on shutting down at half throttle. I never had this problem before. Spark plugs a little sooty, anything I can do with Eli to make it run leaner. Spark plugs were 2 heat ranges too cold. I can try replacing first.
I don't know much about small engine EFI systems, but maybe something to do with the injectors or an o2 sensor?
 
Top