STIHL CHAINSAW MS 170 WON T START General Troubleshooting

Spark Plug

The spark plug is the most frequent point of failure due to carbon fouling or electrode wear. On the MS 170, a blackened tip or cracked insulator prevents the necessary arc to ignite the fuel-air mixture. Replacing this ensures the ignition system is delivering a consistent spark to the combustion chamber.

Zama Carburetor Assembly

The MS 170 utilizes a compact carburetor with very small internal passages that easily clog when fuel is left to sit and evaporate. Because these units often feature fixed jets, they are difficult to clean effectively. Replacing the entire assembly is the industry-standard fix for fuel delivery issues where the saw only starts with fuel primed directly into the cylinder.

Fuel Line Hose

This specific model is prone to the fuel line cracking or becoming porous over time, particularly where it passes through the chassis. A crack in the line allows the fuel pump to suck air instead of gasoline, leading to a lean condition or a total failure to prime. Replacing the line restores the vacuum integrity of the fuel system.