Briggs & Stratton owns the Snapper and Simplicity lawnmower brands and also produces small engines with carburetors for a wide range of mower manufacturers. The 12 horsepower engine is widely used but can face a number of carburetor problems that can result in your mower becoming inoperable pending disassembly of the engine block around the carburetor. Cleaning and rebuilding the 12 HP carburetor may be necessary to salvage your mower, and you can handle this procedure without professional assistance.
Locate the 12 HP engine's muffler at the bottom left of the engine block. It is held in place by two bolts. Remove these bolts with a socket wrench and pull off the muffler.
Take out the gas tank's dipstick and remove the tank's bolts with the socket wrench then pull the tank off.
Locate the distinctive, bowl-shaped 12 HP carburetor. It rests near the middle point of the right side of the engine assembly. The carburetor intake on the back of the carburetor bowl assembly is held in place with several screws. Remove these with a Phillips head screwdriver.
Remove the 12 HP carburetor intake's air filter by twisting and pulling it off the back of the intake piece.
Remove the bolts on the carburetor intake with the socket wrench to disconnect it from the carburetor bowl.
Put a pan under the 12 HP carburetor bowl then loosen the nut on the Briggs & Stratton bowl's bottom to drain any fuel and fluid into the pan. Remove the pan once the bowl completely drains.
Take out the bowl's nut then twist off the carburetor bowl.
Use a carburetor cleaning solution applied with a soft cloth to clean out the inside of the 12 HP carburetor bowl then set the bowl back into place and tighten its nut back to the bottom with the wrench.
Twist the air filter onto the back of the carburetor intake then refasten the intake to the rest of the carburetor on the engine block with the screwdriver.
Replace the gas tank onto the Briggs & Stratton engine with the socket wrench. Insert and tighten each bolt with the wrench before reinserting the dipstick.
Tighten the muffler back onto the 12 HP engine's lower left side with the wrench.