How to Troubleshoot a Briggs & Stratton Quantum 6.5 HP

Park the lawnmower and turn off the Briggs & Stratton Quantum 6.5 HP engine.

Open the engine's hood and find the spark plug on the right side of the Briggs & Stratton Quantum 6.5 HP engine. Make sure the thin, black ignition wire has not become disconnected. Slide it back into the rear insertion point on the Briggs & Stratton spark plug if it has.

Replace the spark plug if the old plug is visibly worn or has black or brown corrosion on its end. Pull the ignition wire from the spark plug's rear and reinsert it into the new Briggs & Stratton spark plug.

Follow the mower battery's red terminal wire back to the solenoid. This wire must be connected to the solenoid's side bolt. Place the wire's end over the bolt and tighten it into place using a socket wrench if necessary.

Adjust the needle valve on the Briggs & Stratton Quantum 6.5 HP's carburetor if the engine is running rough and sputtering. Turn on the engine and turn the valve all the way to the right. Turn the valve gradually back to the left if the Briggs & Stratton engine continues to run rough. Listen to the engine as you make gradual adjustments to the valve until the sputtering stops.

Turn off the engine and find the nut on the underside of the Briggs & Stratton Quantum 6.5 HP carburetor's bowl if engine sputtering problems persist. Place a dish under this nut in anticipation of the gas that will leak out upon removing it.

Loosen and take out the carburetor's nut using a socket wrench. Drop the nut into carburetor cleaning solution and scrub off any buildup and debris. Wait as the gas finishes draining into the dish.

Remove the now loose Briggs & Stratton Quantum's carburetor bowl from the engine assembly and clean out the inside with a cloth. Set it back in place when done.

Tighten the nut into the bottom of the Briggs & Stratton Quantum 6.5 HP's carburetor with a socket wrench.