Gas trimmers are also known by other generic names like weed eaters or weed whackers, and they come in electric and gasoline-powered versions. The electric types are all self-contained and are virtually maintenance-free. Gasoline-powered types, whether they are two-cycle or the newer four-cycle models, all need the same basic tune-up to keep them running efficiently and ready when you need them.
Empty all the old gasoline out of the trimmer and into the oil drain pan. Take this to the nearest automotive service station or hardware store for recycling.
Pull the spark plug boot off of the spark plug.
Attach the spark plug wrench or ratchet with plug socket onto the spark plug by pushing it on firmly. Remove the plug by turning in a counterclockwise rotation.
Replace the old plug with the new one. Hand start it by turning it in a clockwise rotation, then attach the plug wrench or socket and tighten it firmly. Reattach the spark plug boot by pushing it onto the end of the plug.
Remove the air filter. In modern trimmers the air cleaner cover will be held on by a couple of plastic clasps. These need to be lifted up to disengage them, and then the top can be taken off.
Pull out the foam air filter and drop it into your bucket of water. Add in a tablespoon of dish washing liquid and swirl everything around. Knead the filter in this mixture with your hands several times to clean it, then rinse it thoroughly in clean water or with a hose. Allow it to dry.
Fill your gas tank with fresh fuel.
Start you trimmer with the air cleaner cover off. Once running, apply about half throttle and then spray in a one-second burst of carburetor cleaner into the air filter holder. The exhaust will smoke slightly, but this will clean out any gunk inside the passages and jets of your carburetor. Turn off the motor.
Replace the air filter when it is dry and snap the cover back on.