IGNITION SYSTEM
50
Troubleshooting the ignition system
The purpose of the ignition system is to provide a spark
in the combustion chamber at the proper time to ignite
the fuel/air mixture. The steps in troubleshooting the
ignition system are:
1. Examine the spark plug(s) by following the steps
described in the spark plug section of this chap
-
ter.
NOTE: It is convenient to check the compres-
sion when the spark plug is removed for exami-
nation.
2. Connect a spark tester between the spark plug
wire and a good ground point on the engine.
See
Figure 7.1.
Figure 7.1
Spark tester
CAUTION: Never remove the spark plug and
hold it against the cylinder head to test for spark.
The fuel/air mix coming out of the spark plug
hole will catch on fire.
NOTE: It only takes 1,000 volts to jump a .025”
air gap in open atmosphere, it takes 10,000 volts
to jump the same gap at 120 psi, therefore an
open air spark test in not valid.
NOTE: The spark should be a minimum of 10 Kv
(10,000 volts) at pull over speed.
3. Place the stop switch in the run position (Insert
key for snow engines and move throttle to the
full throttle position).
4. Pull the starter rope. If sparks can be seen in the
spark tester, the ignition system is working.
NOTE: If there are sparks present in the spark
tester, install a known-good spark plug and
prime test the engine. If the engine does not
start, the problem is not in the ignition system.
Check the engine’s compression.
5. If no sparks are seen in the spark tester further
testing is required.
6. Test the stop switch by following the steps
described in the stop switch section of this chap
-
ter.
7. If the stop switch is working properly, replace the
module.
8. Inspect the flywheel.
CHAPTER 7: IGNITION SYSTEM
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