Ignition System - Stihl 4180 Series Manual

4.3

Ignition System

Warning:
Exercise extreme caution while
carrying out maintenance and repair
work on the ignition system. The
ignition system. The high voltages
which occur can cause serious or
fatal accidents.
Condition
Engine does not run
Engine runs roughly, misfires,
temporary loss of power
Series 4180 Powerhead
Cause
No spark
Spark plug dirty or faulty
Faulty insulation or break in ignition
coil, ignition lead or short circuit
wire
Spark plug boot is loose
Spark plug sooted, smeared
with oil
Weak spark or no spark
Wrong air gap between ignition coil
and flywheel
Flywheel cracked or damaged
Spark plug dirty or faulty. Check
slide control, ignition coil/lead for
damaged insulation and leakage
current.
Remedy
Check operation of slide control
and ignition module; replace
damaged parts
Clean or replace spark plug
Use ohmmeter to check ignition coil
and lead for break. If break is
detected or resistance is high, fit a
new ignition coil and ignition lead;
check short circuit wire for ground
contact in run position
Press boot firmly onto spark plug
and fit new spring if necessary
Install new spark plug
Faulty insulation on ignition lead or
short circuit wire. Use ohmmeter to
check ignition lead for break. If
break is detected or resistance is
high, fit a new ignition lead.
Reset air gap
Install new flywheel
Clean or replace spark plug.
Replace damaged parts of ignition
system
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