Stihl MS 291

47MS 271 C, MS 291 C
7.4 Testing the Ignition
Module
To test the ignition module, use
either the ZAT 4 ignition system
tester 5910 850 4503 or the ZAT 3
ignition system tester
5910 850 4520.
The ignition test refers only to a
spark test, not to ignition timing.
Using ZAT 4 ignition system
5910 850 4503
– Before starting the test, install a
new spark plug in the cylinder
and tighten it down firmly.
: Connect spark plug boot to the
input terminal (1). Push the
tester’s output terminal (3) on to
the spark plug.
High voltage – risk of electric shock.
– Crank the engine quickly with the
rewind starter and check spark in
the tester’s window (2).
The engine may start and
accelerate during the test.
If a spark is visible, the ignition
system is in order.
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– If no spark is visible in the
window (2), check the ignition
system with the aid of the
troubleshooting chart, b
7.8
Using the ZAT 3 ignition tester
5910 850 4520
– Before starting the test, install a
new spark plug in the cylinder
and tighten it down firmly.
: Connect spark plug boot to the
terminal (2).
: Attach the ground terminal (1) to
the spark plug.
: Use adjusting knob (4) to set the
spark gap to about 2 mm,
see window (3).
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While using the ZAT 3, hold it only
by the handle (4) or position it in a
safe place. Keep fingers or other
parts of your body at least 1 cm
away from the spark window (3),
high voltage connection (2), ground
connection (5) and the ground
terminal (1).
High voltage – risk of electric shock.
– Crank the engine quickly with the
rewind starter and check spark in
the tester’s window (3).
The engine may start and
accelerate during the test.
If a spark is visible in the
window (3), the ignition system is in
order.
– If no spark is visible in the
window (3), check the ignition
system with the aid of the
troubleshooting chart, b
7.8
165RA185 TG
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