Won't Start
Stihl MS170 Won't Start After Sitting
Updated 2026-05-20
A storage-related no-start checklist for Stihl MS170 chainsaws covering stale fuel, spark plug condition, fuel pickup, primer parts, and carburetor checks.
Assume Fuel First
When an MS170 sits with ethanol-blend fuel, varnish, stiff diaphragms, and restricted pickup filters are more common than a failed ignition module.
Drain old fuel, inspect the fuel line for cracking, and verify that the in-tank pickup filter is still attached and moving freely.
Check Spark Before Buying a Carb
Pull the plug and look for fuel fouling, heavy carbon, or a damaged electrode. Match the plug number and gap against the model page before replacing it.
If the plug is wet after repeated pulls, the saw may be flooded; let it clear before assuming the carburetor is bad.
Primer and Serial Split
Primer bulb fitment can vary by serial range. Compare the old bulb and line routing before buying a generic kit.
If the primer will not fill, inspect the bulb, fuel line grommet, pickup filter, and carburetor check valves together.