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190cc Briggs Backfires when warm

#1

Sten4413

Sten4413

Hello,

I have a 190cc B&S lawn mower engine that starts and runs great. After the engine is warm and I go to restart it, i get a backfire. I almost positive its out of the exhaust/muffler. If I pull start it again, it runs great.

What are some things I can check.


#2

M

mechanic mark



#3

B

bertsmobile1

As a push mower engine is stopping unburned fuel is pumped into the muffler where it very slowly dissapates
When you pull the starter the hot / burning exhaustignites this gas in the muffler which causes a pressure wave pushing the piston down when it is trying to go up.
Second pull has no unburned gas in the muffler so off it goes
You may have a partially blocked exit hole due to mud wasps building there over winter .


#4

Sten4413

Sten4413

bertsmobile1 said:
As a push mower engine is stopping unburned fuel is pumped into the muffler where it very slowly dissapates
When you pull the starter the hot / burning exhaustignites this gas in the muffler which causes a pressure wave pushing the piston down when it is trying to go up.
Second pull has no unburned gas in the muffler so off it goes
You may have a partially blocked exit hole due to mud wasps building there over winter .
Click to expand...
I check the exhaust, valves, gas, cleaned the carb and good spark plug. Still popped.
Thanks for the explanation.


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