Backfiring resolution

jp1961

Well-Known Member
Joined
Jul 22, 2013
Threads
39
Messages
785
Hi Guys,

My 4hp Tecumseh (on a Troy-Bilt Junior rototiller) backfired when running at full speed and real bad when the throttle was pulled back to idle.

After searching the web for a cause of backfiring on small air cooled engines, I couldn't find a definitive reason why.

I removed the head on the engine and did replace the rings and shaft seals. I'm guessing carbon buildup on the piston, cylinder head and around the valves was causing a glow plug like firing of the air/gas mixture when the intake valve was open (instead of firing when the spark plug ignited it). Once the carbon was removed with a wire brush the engine doesn't backfire anymore. So I'm posting this for future reference.

Any thoughts?

Jeff
 

bertsmobile1

Lawn Royalty
Joined
Nov 29, 2014
Threads
64
Messages
24,647
:welcome:
Hi Guys,

My 4hp Tecumseh (on a Troy-Bilt Junior rototiller) backfired when running at full speed and real bad when the throttle was pulled back to idle.

After searching the web for a cause of backfiring on small air cooled engines, I couldn't find a definitive reason why.

I removed the head on the engine and did replace the rings and shaft seals. I'm guessing carbon buildup on the piston, cylinder head and around the valves was causing a glow plug like firing of the air/gas mixture when the intake valve was open (instead of firing when the spark plug ignited it). Once the carbon was removed with a wire brush the engine doesn't backfire anymore. So I'm posting this for future reference.

Any thoughts?

Jeff

:welcome::thumbsup:

Been known to happen particularly if the engine is running a touch on the rich side.
 
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