To begin with, let's start with the basics.
- Are you using fresh gas? If not, you need to get some. If there is any old gas/oil mixture in the machine, remove it by pouring it into some sort of container.
- If want to purchase a gas/oil mixture already mixed, a store like Home Depot or Lowes has quart cans at the correct mixures. 50:1 / 40:1 etc. and it's Leaded gasoline usually 91 octane.
Weedeaters will lose their carburetor adjustment over time because of vibration or the fuel mixtures may change. The carburetor settings are crucial for the machine to run properly.
Not all carburetors are the same, but which ever one you have, you will need a special adjusting tool
to do this. You can find adjusting sets locally or here. https://www.amazon.com/HIPA-Carburetor-Adjustment-Including-21-Teeth/dp/B01FAAKN7E/ref=sr_1_3?ie=UTF8&qid=1467833656&sr=8-3&keywords=carburetor+adjusting+tool
Not To do this process, you will need to identify the 2 special
adjusting screws on the top or side of the carburetor.
The screws are highlighted as HI and LO. The HI allows fuel adjustment for the weedeater at full throttle. The LO is for the adjusting the idle.
Try these steps:
1. Adjust both screws clockwise until just seated (tight) using the correct tool (from a set similar to the one above)
2. Rotate the HI screw 1 1/2 turns counter-clockwise
3. Rotate the LO screw 1 turn counter-clockwise
4. Start the machine.
5. When it's running (spitting, coughing...) adjust the LO screw a 1/4 turn either way until you get a smooth idle.
6. Pull handle to run at full throttle. If the engine is sputtering then it's getting too much fuel....adjust the HI 1/4 turn clockwise checking to see if the engine runs smoother.
7. When you get the weedeater running smoothly, there are no further adjustments to be made. Just make sure you are using FRESH gas/oil that hasn't been sitting longer than 30 days.