Stihl MS 391 User Manual

48 MS 311, MS 391
7.8 Ignition System Troubleshooting
Machine does not run
Stop switch:
– in position "F"?
Check the spark plug:
– Smeared with oil, black?
– Sooted?
– Electrode gap correct?
– Contacts shorted?
– Clean, readjust or replace the plug, b 7.4
Check the 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,
b 7.5
Test ignition system:
with ZAT3 or ZAT4
(use ZAT 3 as main spark gap
see TI 32.94),
b 7.4
1

Stihl MS 391 Specifications

General

Motor type	2-stroke motor
Chain gauge	1.6 mm
Chain pitch	3/8 \
Automatic oiling	Yes
Oil tank capacity	0.35 L
Fuel tank capacity	0.6 L
Engine displacement	64.1 cm³
Engine power	4.4 hp
Power source	Gasoline

Weight and Dimensions

Weight	6200 g