Stihl FC 90 - Testing the Ignition System

54 Series 4180 Powerhead
Using ZAT 4 ignition system
tester 5910 850 4503
– Before starting the test, install a
new spark plug in the cylinder
and tighten it down firmly, b
3.4
: Pull the boot off the spark plug
VA
208RA053
321
and connect it to the input
terminal (1). Push the tester’s
output terminal (3) onto the spark
plug.
– Crank the engine quickly with the
rewind starter (min. 1,000 rpm)
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. If no spark is
visible in the window (2):
– Check ignition system with aid of
troubleshooting chart, b
8.4
Using ZAT 3 ignition system
tester 5910 850 4520
– Before starting the test, install a
new spark plug in the cylinder
and tighten it down firmly, b
3.4
: Pull the boot off the spark plug
VA
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ZAT 3
5910 850 4520
3
2
1
and connect it to terminal (2).
: Attach the ground terminal (1) to
the spark plug.
: Use adjusting knob (3) to set the
spark gap to about 2 mm.
: When using the ZAT 3, hold it
only by the handle (4) or position
it in a safe place. Keep fingers or
other parts of body at least 1 cm
away from the spark window (3),
the high voltage connection (2),
ground connection (5) and the
ground terminal (1).
High voltage – risk of
electrocution.
– Crank the engine quickly with the
rewind starter (min. 1,000 rpm)
and check spark in the tester’s
window (3).
The engine may start and
accelerate during the test.
If a spark is visible, the ignition
system is in order.
If no spark is visible in the window
(3):
– Check ignition system with aid of
troubleshooting chart,
b
8.4
Reassemble in the reverse
sequence.
8.3 Testing the Ignition
System