Jeep 1987 Wrangler Workshop Manual page 622

ELECTRICAL
IGNITION SYSTEM - MOTORCRAFT (6-Cyl. Engine)
When a tachometer is required for engine
testing or tune-up, connect it using an alligator
jaw-type connector (A).
SEE
I.S.
N
O
T
E
S
86313
IGNITION SYSTEM
DIAGNOSIS
For diagnostic purposes, ignition system
problems are considered in three categories:
1. Complete failure
2. Intermittent failure
3. Spark knock (pre-ignition)
Complete failure is always a no-ignition
situation. The engine will not start. If a complete
failure occurs when the engine is operating, it
will not restart.
Intermittent failure is temporary. The engine
may not start on the first try, but will eventually
start. If an intermittent failure occurs when the
engine is operating, it may falter and possibly
stop. If it stops, it will restart and will continue to
operate intermittently.
Spark knock (pre-ignition) is not actually an
ignition system failure. The engine will start and
will continue to operate. If not corrected, spark
knock can cause extensive internal engine
component damage.
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