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Mend Briggs & Stratton 120000 Engine Spark Air Throttle

Briggs & Stratton Quantum 120000 engine hunting?

The above engine on my lawn mower has started to continuously "hunt". I.e. it goes brrm, brrm all the time. Like someone continuously pressing the throttle pedal on a car. I'm told the carb doesn't have any adjustment. The spark plug connection is good and the air filter is clean. Any clues?

Pete
July 2009

Briggs & Stratton Briggs & Stratton 120000 Garden Tools, Lawn Mowers Engine Spark Air Throttle

This is not a carb-on-the-tank engine - there is no diaphragm. The symptoms are of a lean mixture - older Quantums DO have a mixture adjstment screw, but most don't. Drain the float bowl (a blob of water in the bottom can patially block the jet and give these symptoms. If not, you will have to strip and clean the carb, running a piece of copper wire through all the jets.

phil_saunders(a)bigfoot.com

Phil Saunders
July 2009

there is a gasket diapragm between petrol tank and the carb.these go brittle after a time especially if you leave petrol in tank over winter.you can get these from dealer but will need to take serial no of engine.also check the fine regulator spring has not been stretched or come off(this is on top of carb between a lever and the connection to the fan vane about 2 inches long.

ivan
July 2009