Clean Air Filter

• Air filters trap particulate matter from the air and keep them from entering the cylinder, which, if it did make it, would scour the edges of the bore and chamber walls. These air filters also act as a secondary cooling system for the engine. However, if the filters can't work, the air will stop flowing and the engine won't start. Filters can get dirty quickly, especially if you're using one in dusty conditions. Clean the air filter every 8 to 10 hours of operation, washing it in soapy water and letting it dry thoroughly before using it again.
  
  

Clean Fuel System

• The fuel system keeps the supply of fuel circling throughout the engine, so there's always an adequate supply for the engine. This fuel cycle can get interrupted at many different points throughout the system, so start at the originating point and follow it up to the carburetor. Dump out any gas older than one week, and start with fresh gas. Clean the tank with a brush and rag, pull out the fuel filter and give it a thorough cleaning in soapy water; or replace it if it can't be cleaned. Change the fuel lines at least once every other season.
  
  

Sparking Issues

• The spark plug needs to discharge the proper amount of electricity at just the right time for the fuel to ignite in the cylinder. The spark originates in the ignition module, travels up the plug wire and goes to the spark plug. If the spark plug is fouled or dirty, the tip will look black or corroded, and the spark plug will not discharge a high enough voltage spark, which will require spark plug replacement. Examine the rubber boot used to connect to the spark plug for any loose connections. Leave all other electrical repairs to a professional.
  
  

Carburetor Issues

• Unfortunately, a lot of starting problems on a Weed Eater trimmer occur in the carburetor. As the carburetor ages, the fuel passages and jets will gradually get clogged, shutting down the flow of fuel. Also, the screws and levers that regulate the flow of gas can also get out of alignment or stuck closed or open. The diaphragm the carburetor uses to suck more fuel into the carburetor will also tear or get deformed. Many starting problems can be solved through a thorough carburetor cleaning, which should also be left to a professional.