If a Craftsman lawn mower loses power while you are mowing grass, some causes are immediately evident. Of course, it must have a source of power, so make sure that the mower tank has gasoline in it, or that an electric mower is plugged in or the circuit breaker is not tripped. Also, make sure that you are not walking too fast, causing the mower to fall behind your speed. Beyond those most simple of considerations, troubleshoot the lawn mower to find and remove other causes as to why the mower shuts off.
Look down at the mower, to see if the mower rear is dragging in thick grass. Squeeze the adjustment lever on each of the lawn mower wheels out towards the wheel. Move the lever forward, to raise the mower's cutting height.
Lift the mower's side discharge guide, and scrape out any trapped masses of grass clippings, using a brush or putty knife.
Remove the engine oil fill cap/dip stick, and check the mower's level of oil. Move the mower to a level surface, if the oil is too low or too full.
Pull the spark plug wire off the mower spark plug. Set a container on the ground, and tip the mower onto one side. Allow all of the oil to drain into the container and set the mower back upright.
Slowly refill the mower engine with oil, up to the "FULL" line. Screw the oil fill cap/dip stick back on.
Remove the mower's air filter, according to the specific instructions for your particular Craftsman mower model, and inspect it. Wash off a dirty filter with water, or replace an old or damaged air filter.
Remove the spark plug wire from the mower's spark plug, if it is not already removed. Tilt the mower on its side, if you have a lot of grass clippings, leaves and other materials trapped underneath the mower.
Place a wood block between the blade and the mower deck, to further prevent the blade from moving. Scrape all the clippings and other items off the bottom of the mower, using a brush or putty knife. Remove the wood block.
Set the mower upright. Place the spark plug wire back over the end of the spark plug.