8-6
IGNITION SYSTEM
The ignition system consists of the magneto as-
sembly, ignition coil, spark plug and ignition wiring.
If a problem with the ignition system is suspected,
the spark plug can be inspected and an ignition
spark check can be made without removing the
genset from the vehicle. Perform the spark plug,
ignition coil and ignition wiring checks before pro-
ceeding to the Magneto Assembly section.
WARNING
Electrical shock can cause severe
personal injury or death. Do not touch electrical
wiring or components during testing. Discon-
nect electrical power by removing the starting
battery negative (–) cable before handling elec-
trical wiring or components. Do not connect
meters while circuit is energized. Use rubber in-
sulative mats placed on dry wood platforms
over floors that are metal or concrete when test-
ing electrical equipment. Do not wear jewelry or
damp clothing (particularly wet shoes) or allow
skin surfaces to be damp when handling electri-
cal equipment.
Spark Plug (E2)
Remove the spark plug and inspect the electrode. If
the spark plug has carbon deposits, use a wire
brush to clean it. If the spark plug is badly fouled or
deformed, replace it. Measure and reset the spark
plug gap as shown in Figure 8-4. See Section
2.
Specifications
. An examination of the spark plug
can often help diagnose an engine problem. Refer
to the following spark plug conditions:
• Carbon Fouled – Check for a poor high tension
lead connection, faulty choke operation, rich
fuel mixture or dirty air filter.
• Oil Fouled – Check for low compression.
• Burned or Overheated – Check for leaking in-
take manifold gasket, lean fuel mixture or incor-
rect spark plug type.
• Splash Fouled – Check for accumulated com-
bustion chamber deposits. See
Rocker Arms,
Push Rods and Cylinder Head
section on Page
10-3.
• Light Tan or Gray Deposits – Normal plug color.
If the spark plug is in good condition, proceed to the
Ignition Coil
section, following.
Ignition Coil (T1)
The ignition coil is a transformer that steps up the
magneto output voltage to about 20,000 volts for
spark plug firing. The coil consists of a primary and a
secondary winding. Perform the following checks:
WARNING
Gasoline vapor is extremely flam-
mable, and can result in severe personal injury
or death if ignited. Make certain that no gasoline
or other flammable fumes are present. Park the
vehicle in a well-ventilated area, and leave the
genset compartment door open for several min-
utes before performing this test.
Ignition Spark Check:
This checks all of the igni-
tion system components and wiring.
1. Make sure the engine oil level is adequate and
that the genset is level.
2. Remove the spark plug, reconnect the spark
plug lead and ground the plug side electrode to
bare metal on the engine.
3. Do not touch the plug or plug wire during test-
ing. Crank the engine and observe the plug. If
a good spark is observed, the ignition system
is good. If no spark, or a weak spark is ob-
served, proceed to the coil winding check.
ES1374s
SPARK PLUG GAP
(SEE SECTION 2.
SPECIFICATIONS)
FIGURE 8-4. MEASURING PLUG GAP
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