STIHL chainsaw Ignition System Troubleshooting guide
Engine does not run
Check the spark plug:– Smeared with oil, black?
– Electrode gap correct?
– Contacts shorted?
Clean the plug, reset or replace
Check spark plug boot: – Firmly seated on plug (leg spring)?
– Leg spring hook in center of ignition lead?
– Boot damaged?
If necessary, install new spark plug boot and/or leg spring.
Test ignition system with ZAT 3 or ZAT 4 (use ZAT 3 as main spark gap – see TI 32.94)
YES-> GO TO (4)
NO–>Check air gap and reset if necessary
Check flywheel: Pole shoes have turned blue? Install new flywheel
Disconnect short circuit wire from ignition module
Check ignition lead: – Severe chafing? – Spark plug boot: Holes/cracks? Resistance: spark plug boot to ground: spec. 1.5 – 12 kΩ – Check resistance of ignition lead: spec. < 10 Ω, If necessary, install new spark plug boot and/or ignition lead.
Check operation of setting lever – Short circuit wire chafed? – Contact gap (contact springs) If necessary, install new ignition lead and/or contact springs Re-connect short circuit wire
(4) NO>Install new ignition module
YES> Check “I“/“O“ function on setting lever or separate stop switch.
NO> Look for fault in fuel system or carburetor, check engine for leaks, check position of flywheel on crankshaft.