John Deere stx38 - Manual (Page 151)

3/21/97
4 - 67
ELECTRICAL TESTS AND ADJUSTMENTS
IGNITION SPARK TEST
Reason:
To determine condition of ignition system.
Equipment:
• D-05351ST Spark Tester
Connections:
1. Remove ignition module high tension lead (B) from
spark plug (A).
2. Connect spark tester lead (D) to spark plug (A).
3. Connect high tension lead (B) to tester (C).
IMPORTANT: DO NOT adjust spark tester gap (D)
beyond 5.0 mm (0.200 in.) as damage to ignition
system could occur.
4. Adjust spark tester gag (D) to 4.2 mm (0.166 in.)
with screw (C).
Procedure:
1. Crank or start engine. Watch spark at tester gap.
Results:
• Steady, strong, blue spark - ignition is good. If
engine will not start, check fuel supply and engine
compression.
• If spark is weak, or no spark, install a new spark
plug.
• If spark is still weak or still no spark, see Adjust
Ignition Module Air Gap and/or Ignition Module
Test..
Specification:
Spark Plug Gap . . . . . . . . . . . . . . 1.0 mm (0.040 in.)
Spark Plug Torque . . . . 38—43.4 N•m (28—32 lb-ft.)
IGNITION MODULE AIR GAP
ADJUSTMENT
Reason:
To adjust the air gap between the ignition module and
the flywheel to a specific dimension needed for proper
ignition timing.
Equipment:
• 0.25 mm (0.010 in.) feeler gauge
Connections:
1. Put transaxle in neutral.
2. Put key switch in OFF position.
3. Remove blower housing.
Procedure:
1. Turn flywheel magnet away from ignition module.
2. Loosen ignition module mounting screws and hold
module as far back as possible.
3. Turn flywheel magnet so it is centered on ignition
module.
4. Insert 0.25 mm (0.01 in.) feeler gauge (A) between
flywheel magnet and all three ignition module
polls. Allow module to draw against feeler gauge
(A) and flywheel magnet.
5. Hold module coil in this position and tighten
mounting screws to specification.
6. Turn flywheel to remove feeler gauge.
7. Install blower housing.
Specifications:
Ignition module air gap
. . . . . . . . . . . . . . . . . . . . . . . . . . 0.25 mm (0.01 in.)
Ignition Module Cap Screws
. . . . . . . . . . . . . . . . . . . . 4.0—6.2 N•m (35—55 lb-in.)
B
C
A
M55937
E
D
A
M58360