Service Manual

IGNITION TIMING
The ignition timing is preset at the factory and is not
adjustable.
For troubleshooting purposes, it is possible
to make an approximate check of the ignition timing
using reference marks on the blower housing and
flywheel (Figure 2). This check can be performed by a
continuity test.
BLOWER
TIMING
FIGURE 2. IGNITION TIMING MARKS
4. Rotate the flywheel slowly by hand in the clockwise
direction until the voltmeter reading switches from
approximately 1 volt to battery voltage. At this point,
one of the chaff screen screws should lie between
the two reference marks on the blower housing. To
recheck timing, the flywheel must
be rotated another
complete revolution in the clockwise direction.
Moving the flywheel back and forth across the
reference timing mark will not activate the electronic
ignition control.
5. Install spark plugs and wires.
,
IGNITION COIL
To test primary and secondary windings within the
ignition coil first make sure the ignition power is off and
coil is at room temperature of 70°F (21 "C).
1. Use a Simpson 260
VOM or equivalent.
2. Place
a black lead on negative (-) coil terminal and
red lead to positive
(+) coil terminal. Primary
resistance should read between 2.90-3.60 ohms.
3. Change resistance setting on ohmmeter. Place
ohmmeter leads inside of spark plug cable holes
(Figure
3). Secondary resistance should read
between
14,500-1 9,800 ohms.
4. If either of the above resistances are not within
M-1675 specification, replace coil.
Continuity Test
1. Pull spark plug wires off spark plugs and remove
spark plugs.
Failure to remove spark plugs
before turning engine over may
result in engine starting, which may cause severe
personal injury.
2. Turn ignition on.
3. Connect a voltmeter between the negative
(-) coil
terminal (larger diameter of the two threaded posts)
and a good engine ground.
d
The electronic ignition will
deliver full voltage
to the spark
plugs even when rotated
by hand. Care should be
taken to avoid an electrical shock.
FIGURE 3. COIL TEST