Briggs and Stratton 104M02 Surges

[Mechengineer1218]

Hi All,

I have a 7.25hp Briggs 104M02 motor on a Toro push mower that is surging. I replaced the carb and fuel line. Also blew out the fuel tank and still surges.
If I hold the throttle plate (what the linkage hooks too) the mower will run smooth. Any ideas?
Thanks.

 

[bertsmobile1]

You got an air leak.
Start with the easy bit by spraying WD 40 or similar all around the carb / engine interface.
If you get clouds of white smoke or the engine faulters you have an air leak there.

Hard bit remove the blower housing and you will see the tube the carb attaches to goes all the way across the engine.
Remove it and check it carefully for splits.
Also check the very thin gasket between it and the engine.
When tou replace it remember the 1/16" bolts are not for securing the USS Missourri