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DTX · 05-30-2009, 03:51 AM

Briggs & Stratton 3.5 hp Quantum on push mower.
Many years old but was running great.

This mower just got where it would not run. Stopped running while I was using it.
I can get it to run at a low rpm only with some missing if I have the filter off the carb and a screwdriver holding the auto chock flap open. But no way I can get it to increase rpm.

I since tried replacing the diaphram gasket in between carb and gas tank. Also put in new spark plug. No improvement.

I then went into the motor, found the flywheel shaft key broken and the flywheel a bit behind on position so I installed a new key and reasembled. Still no improvment.

I then went into the motor. Did not see anything broken. Installed new seals and case gasket. I checked valve clearances. Exhaust valve okay. Intake valve have no clearance so I ground the end of the valve stem to give a few thousands clearance.

Reinstalled and the motor still would not run properly. It was doing the same thing as in the beginning. idled running with a screw driver holding the choke open.

Would anyone know what the problem might be?

05-30-2009, 03:51 AM	#1 (permalink)
DTX Registered User Join Date: Sep 2004 Posts: 6 OS: N/A	Briggs Stratton motor not running Briggs & Stratton 3.5 hp Quantum on push mower. Many years old but was running great. This mower just got where it would not run. Stopped running while I was using it. I can get it to run at a low rpm only with some missing if I have the filter off the carb and a screwdriver holding the auto chock flap open. But no way I can get it to increase rpm. I since tried replacing the diaphram gasket in between carb and gas tank. Also put in new spark plug. No improvement. I then went into the motor, found the flywheel shaft key broken and the flywheel a bit behind on position so I installed a new key and reasembled. Still no improvment. I then went into the motor. Did not see anything broken. Installed new seals and case gasket. I checked valve clearances. Exhaust valve okay. Intake valve have no clearance so I ground the end of the valve stem to give a few thousands clearance. Reinstalled and the motor still would not run properly. It was doing the same thing as in the beginning. idled running with a screw driver holding the choke open. Would anyone know what the problem might be?