To run a carburetor properly on your string trimmer, you must follow three simple steps in order to get it to run properly. If you make sure the compression, gas, and spark are ready to go, you are on your way to a successfully running carburetor.
Step 1 - Testing the Air and Compression
Remove the air filter cover with a screwdriver. Once the air filter is removed, clean it. You can either wipe it down with a damp towel, or slightly smack the cover to remove any dust or debris that is inside it. Some filters if too dirty will need to be replaced.
Step 2 - Removing the Cover of the Muffler
Remove the cover with a screwdriver. Next pull out the spark arrestor screen from the muffler. Clean the screen with the damp rag. To clean any small crevices use the toothbrush.
Step 3 - Check to See if the Starter Works
Hold the string trimmer by its starter string. If the string can be used out from underneath the weight of the engine then this means that the air compression is low. If the air compression is low you will need to retune the carburetor adjustment screws.
Step 4 - Testing the Spark Plug
Use the screwdriver to remove the spark plug boot off of the spark plug. Next pour a little gas over the spark plug and clean it off with the rag. Put the spark plug back into the rubber boot. Hold both of them adjacent. Now you can pull on the starter cord to see if there is a spark or not. If a spark does not result replace the spark plug. Then test the ignition cable, starter, and starter coil if a spark still does not result.
Step 5 - Testing for Fuel
Drain the fuel tank and clean it with carburetor cleaner. Disconnect the fuel line from the carburetor and remove the old fuel filter and fuel line. Check the primer bulb for any damage or cracks. Replace if needed. Pump the primer bulb a few times to make sure it is full of gas. First start the trimmer until it pops. You will have to check all the settings for this. Move all the way up to setting three and hold down the throttle as you start the trimmer.
Step 6 - Retuning the Carburetor
If the trimmer starts, retune the carburetor’s adjustment screws. All three should be retuned: the high, low, and ideal settings.
Step 7 - Disassembling the Carburetor
Dissemble the carburetor and place the parts in a carburetor bath. Leave them in for a few days to soak. Scrub the parts with a heavy brush to make sure they are thoroughly clean. Replace any old parts from a carburetor kit.