Test 20 - Check Ignition Spark; Test 21 - Check Spark Plug(S) - DeWalt DXGN4500 Manual

Results
If battery voltage is indicated on meter but motor
1.
did NOT operate, remove and test starter motor for
proper operation independent of engine.
If battery voltage was indicated and Starter Motor
2.
tried to engage (pinion engaged) but engine did not
crank, check for mechanical binding of engine or
rotor.
NOTE: If a starting problem is encountered, the engine
itself should be thoroughly checked to eliminate it as the
cause of starting difficulty. It is good practice to check
engine for freedom of rotation by removing spark plugs
and turning crankshaft over slowly by hand to be sure it
rotates freely.
WARNING
Personal injury. Never rotate engine with spark plug
removed. Rotating engine with spark plug removed
could result in death or serious injury.
NOTE: Arcing at the spark plug ends may ignite the
gasoline vapor exiting the spark plug hole.
Figure 1-4. Starter Motor (SM)
Checking The Pinion
See Figure 1-5. When starter motor is activated, the
pinion gear should move and engage flywheel ring gear.
If pinion does not move normally, inspect pinion for
binding or sticking.
Figure 1-5. Check Pinion Gear Operation
Diagnostic Repair Manual
Test 20 – Check Ignition Spark
Procedure
A commercially available spark tester may be used to
test engine ignition system. One can also be purchased
from DeWalt (Part No. 0C5969).
Disconnect spark plug lead from spark plug.
1.
Attach high tension lead to spark tester terminal.
2.
See
3.
tester clamp by attaching to cylinder head.
(000564)
003992
Crank engine rapidly. Engine must crank at 350
4.
rpm or more. If spark jumps tester gap, assume the
ignition system is working properly. Repeat on
remaining cylinder spark plug.
If spark jumps tester gap intermittently, the problem
5.
may be in the Ignition Magneto.
Results
Refer to flow chart.
Test 21 – Check Spark Plug(s)
Procedure
See Figure 1-8
Clean with commercial solvent. DO NOT BLAST CLEAN
SPARK PLUGS. Replace spark plugs if badly fouled, if
ceramic is cracked, or if badly worn or damaged.
Section 3 Engine Diagnostic Tests
Figure 1-6 and Figure
Figure 1-6. Testing Ignition System
Figure 1-7. Checking Engine Miss
and Figure 1-9. Remove spark plugs.
1-7. Ground spark
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