Mercury MerCruiser MCM 454 Mag MPI Service Manual page 680

SERVICE MANUAL NUMBER 23
Chart A-7 (4 of 6): Ignition System Check (Continued)
Step
Index
90-861326--1 MARCH 1999
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Action
1. Disconnect distributor 4-wire
connector.
4
2. Check for secondary spark.
Is Adequate Spark Present?
1. Reconnect distributor 4-wire
connector.
2. Check for secondary spark
5
from the coil tower using a
known good coil wire.
Is Adequate Spark Present?
1. Disconnect distributor 2-wire
"C/+" connector harness.
2. Ignition "ON," engine "OFF."
3. Using DVOM, check voltage
at "+" and "C" terminals of the
6
2-wire distributor harness
connector.
Is Voltage Reading Greater
Than The Specified Value At
Both Terminals?
Is Voltage Reading Less Than
7 The Specified Value At Both
Terminals?
1. Reconnect distributor 2-wire
connector.
2. Ignition "ON" engine "OFF."
3. Using DVOM, check voltage
from tach terminal to ground.
4. The tach terminal can be
8
accessed at the 5-wire boat
harness connector. The tach
circuit is the WHITE wire CKT
121.
Is Voltage Reading Within The
Specified Value?
Is Voltage Reading Greater
9
Than The Specified Value?
1. Using a test light connected
to ground, probe tach termi-
nal at the 5-wire harness con-
10 nector.
2. Observe the test light while
cranking engine.
Is Test Light Blinking?
GENERAL SYSTEM DIAGNOSTICS
Value(s) Yes
_
Go to Step 18
_
Go to Step 19
10 volts
Go to Step 8
10 volts
Go to Step 20
1-10 volts
Go to Step 15
10 volts
Go to Step 10
Go to Step 13
No
Go to Step 5
Go to Step 6
Go to Step 7
Go to Step 21
Go to Step 9
Go to Step 22
Go to Step 11
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