Test 57 - Check Condition Of Spark Plugs - Generac Power Systems 7 kW NG Repair Manual

Section 4.5
Diagnostic Tests
system.
Figure 135. Checking Ignition Spark
V-Twin Only
8. Repeat Step 1 through 7 on the second cylinder.
Note: A sheared flywheel key may change ignition timing
but sparking will still occur across the spark tester gap.
Figure 136. Checking Engine Miss
Results
1. If no spark or very weak spark occurs, proceed to Test 59.
2. If spark is present and the engine still will not start,
proceed to Test 57.
3. When checking for engine miss, if sparking occurs at
regular intervals, but an engine miss continues, proceed
to Test 57.
4. When checking for engine miss, if a spark miss is readily
apparent, proceed to Test 60.
Page 128
PART 4
TEST 57 – CHECK CONDITION OF SPARK
PLUGS
Discussion
If the engine will not start and Test 55 indicated good ignition
spark, some possible causes could be fouled or damaged
electrodes. An engine miss may also be caused by defective
spark plug(s).
Procedure
1. Remove spark plug(s) and inspect for any visible damage,
refer to Figure 137 for types of engine related spark plug
problems.
2. Replace any spark plug having burned electrodes or
cracked porcelain.
3. Refer to Figure 138. Using a wire feeler gauge set the gap
on new or used spark plugs as per Table 23.
NORMAL
PRE-IGNITION
Figure 137. Spark Plug Conditions
Figure 138. Checking Spark Plug Gap
ENGINE/DC CONTROL
MISFIRES
DETONATION