Can the Inproper Mixing of Oil to Gas Cause Leaking in a Weed Eater?

Oil-to-Gas Ratio

• The oil-to-gas ratio for a Weed Eater is 40-to-1, using regular unleaded gasoline at an 87 octane, combined with a high-quality, air-cooled two-cycle engine oil. This ratio allows the engine to ignite the fuel at the proper temperature and gives the engine the right amount of compression to keep it going. The ratio is set at the factory and provides a guideline for operators to achieve the best results when using their trimmers.

Improper Mixing Damage

• If the fuel is mixed improperly, it can either be too rich, with too much oil in the mixture, or too lean, with too little oil. The latter mistake will cause serious engine problems, as the fuel will ignite at a much hotter temperature, risking a blowout of the piston seals and damage to the crankcase. A mixture that’s too rich will burn at a lower temperature and leave behind unburned fuel deposits in the cylinder and muffler, which can cause damage, but not usually a leak.

Causes of Leaks

• A fuel blockage is a likely culprit when a Weed Eater leaks. If fuel gets blocked somewhere in its circuit, compression may push the excess fuel out of the carburetor or fuel hoses. If the fuel mixture was too lean, the added compression could possibly cause a fuel leak, though other, more serious engine damage is likely to occur far sooner. Leaks usually happen when there's a buildup of dirt, grass and other foreign matter in the fuel lines, the carburetor or the fuel tank.

Sources of Leaks

• Finding the source of a leak can be the most challenging aspect of this problem. You should start the investigation by cleaning the Weed Eater’s outer engine completely and trying to follow the leak back to its source. With the excessive vibration of the engine, however, this can be misleading. Common areas for leaks include the connecting point from the fuel tank to the main fuel line; a hole in either of the fuel lines; a hole in the primer bulb; a connection with the fuel hose and the primer bulb; the connection with the fuel hose and the carburetor; the carburetor; and the gasket between the carburetor and the intake manifold.