Problems with 2-cycle engines

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This page includes weed eater engines (blowers, cut off saws, chain saws, etc.), and lawn mower 2-cycle engines.

ENGINE WILL NOT START

1.No fire to the spark plug. Remove stop wire from ignition module and remove spark plug. Pull engine over. If you have fire now, then there is a bad switch or a grounded wire. If you still do not have fire, then the points (if equipped) are bad, ignition module is bad or spark plug is faulty.

2.Hard diaphragms in carburetor. Old gas will eventually make the diaphgragms hard in the carburetor, preventing the pumping action that it required for the fuel to move through the carburetor. Replace the diaphragms and the filter screen.

3.Clogged fuel filter (if equipped) or clogged internal filter screen. Replace both.

4.Extremely low compression. In small 2-cycle engines, (blowers, chain saws, etc.) compression is vital in order for the engine to run correctly. If you are unable to get at least 150 PSI, then the piston and cylinder are scored and need to be replaced. Scoring is caused by the engine running too lean, too fast, too hot, or the wrong fuel-to-oil ratio.

ENGINE HESITATES

1.Stopped up fuel filter. Replace with identical new fuel filter.

2.Carburetor set slightly lean. Open the high speed needle about 1/8 of a turn.

3.Hard diaphragms in carburetor. Old gas will eventually make the diaphgragms hard in the carburetor, preventing the pumping action that it required for the fuel to move through the carburetor. Replace the diaphragms and the filter screen.

ENGINE RUNS FASTER THAN NORMAL

1.Leaking gasket A leaking gasket at the cylinder base or a carburetor mounting gasket will cause the engine to "suck air" and make it run faster than normal. This is a serious problem and must be repaired promptly.