Evinrude E-tec 75 HP, Service Manual, Page: 112 / 344

112
SYSTEM ANALYSIS
START CIRCUIT
Voltage Testing
Use a digital multimeter to check voltages. Identify
all wiring and circuits prior to performing any volt-
age tests. Refer to Wiring Diagrams and descrip-
tions of the various systems for specific
information on each circuit.
55 V Circuits
All 55 V circuits are supplied 12 V when the key
switch is ON, the
EMM
is powered up, and the
outboard is not running.
Stator output supplies 55 VAC to the rectifier cir-
cuits of
EMM
once the outboard is running. The
initial cranking voltage is 30 V or higher and
increases to 55 V when outboard is running.
Ignition Circuit
Ignition voltage displayed on the engine
Monitor
screen of the diagnostic software will have
approximately 0.1 V when the key switch is ON,
the
EMM
is powered up, and the outboard is not
running (electric start models). This voltage
increases to 130 V to 220 V with the outboard run-
ning.
Perform voltage tests on all related circuits and
compare voltage readings. Check voltages while
Dynamic Tests
are activated.
Identify erratic or lower than expected voltage
readings. Determine if the voltage source or the
wiring and connections of the circuit are the prob-
lem.
START CIRCUIT
The start circuit provides the required current to
the starter motor and associated electrical circuits.
Electric Starter Operation
The starter must engage and turn the flywheel. A
minimum cranking speed of 300 RPM must be
achieved for the outboard to start.
Optimum starter performance is achieved by pro-
viding:
•
Proper battery capacity (640CCA)
•
Cables capable of transferring the amperage
•
Low resistance battery and cable connections
•
A solenoid capable of switching the current
These “high amperage” start circuit components
provide the battery current required to crank and
start the outboard (electric start models). Check
the quality and condition of the following:
12 V Marine Battery
•
Battery type, capacity, and condition
•
Condition of battery posts, terminals, and con-
nections
•
Battery switch type, capacity, and connections
Refer to Battery Installation on p. 34 for battery,
terminal, and cable requirements.
Starter Solenoid
•
Starter solenoid and connections
•
Starter solenoid ground, terminal “B”
•
Starter cable (solenoid to starter motor)
•
12 V from solenoid terminal (POS) and engine
harness (red wire) to 10 A fuse
1. Main battery cable
2. Star washer
3. Battery post
DR6495
3
1
2