OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines 3hp briggs not running properly

Hi all my first tech question I have just purchased a scott bonner mower with a 3hp engine got it for a bargain as it was not running
I changed the fuel put a plug from my other mower which has a 3.5 briggs engine and she started straight away.
Now that I have it running the engine which has throttle control on the engine but not a control on the mower handle it runs at a lot lower revs than it should even on full throttle.
I removed the air cleaner and cleaner base and can manually get it running faster by moving the lever which has the idle screw but when I do the revs fluctuate badly as though it is running out of fuel.
I have noticed the bit where you adjust the idle screw the screw does not return so the screw does not touch its return position if it do it manually it stalls if you push the little lever type thing where the screw is the other way the revs go right up but that is when it does the fluctuation
Any advice or should I just buy a new carb which most likely to be cheaper than sending it to a shop?

sounds like the governor set up is all out of whack & the needle screw setting. The screw on the arm that moves is the idle set stop screw

Photos would be good to see.. Base setting for needle jet screw is 1 1/5 to 2 turns open from full closed as a start point..

Hi superdooper will post pics tomorrow
Where is needle jet screw is it the air/fuel screw ?at bottom of carb played around a bit with that made no difference

yes....best to adjust needle at high rpm... From start point slowly screw in till it starts running rough (too lean) now go back out slowly till it runs rough again (to rich) paying attention to the slot position on the screw at each point. finally screw back in half way between the two points.. once you get the throttle set up right that is.

Hi gtman.
I find the best way to get the best information on any equipment is to provide details of the motor from the identification details.
With a Briggs and Stratton, you can get the details from the cowling that states the Model/Type/Code as shown in this photo: -

This information, not only gives more precise detail of the motor in question but, with Briggs and Stratton, you can use it to get specific information and exploded diagrams (with part numbers) from their website.
Hope this is of assistance.
Regards
Daryl

You should see a spring in front of the needle screw.. (not the idle set screw arm)