Mercury 90 Service Manual

90-830234R3 DECEMBER 1997 ELECTRICAL - 2B-7
If visual inspection determines that battery connec-
tions and wiring are OK, perform the following stator
and rectifier tests.
STATOR OHMS TEST
(ALTERNATOR COILS ONLY)
NOTE: Stator can be tested without removing from
engine.
1. Disconnect both yellow (stator leads) from volt-
age regulator/rectifier, or terminal block.
2. Use an ohmmeter and perform the following test.
IMPORTANT: If stator is mounted on engine,
black stator lead (if provided) must be grounded
to powerhead when testing.
3. Replace stator if readings are outside ranges
shown.
NOTE: Resistance varies greatly with temperature.
Measurements should be taken with an ambient tem-
perature range of 65 to 85 degrees F.
9 Ampere Manual Stator
Test Leads
Resistance
(Ohms)
Scale
Reading
Between Yellow Stator
Leads
0.16 - 0.19* R x 1
Between Either Yellow
Stator Lead and
Engine Ground
No Continuity R x 1000
16 Ampere Stator
Test Leads
Resistance
(Ohms)
Scale
Reading
Between Yellow Stator
Leads
0.16 - 0.19* R x 1
Between Either Yellow
Stator Lead and
Engine Ground
No Continuity R x 1000
* DC Resistance of these windings generally is less than
1.5 Ohms. If a reading resembling a short is obtained,
this would be acceptable.
ALTERNATOR SYSTEMS TEST (RED STATOR)
9 Ampere Manual Stator
IMPORTANT: Rectifier (optional accessory) must
be functioning properly for accurate test results
to be obtained.
1. Remove RED lead from (+) terminal of rectifier.
2. Connect RED (+) ammeter lead to rectifier (+) ter-
minal and BLACK (–) ammeter lead to RED recti-
fier lead.
3. With engine running at the indicated RPM, the
ammeter should indicate the following approxi-
mate amperes:
RPM AMPERES
9 Ampere
Idle 0
9
Ampere
Manual Stator
1000 0.6
2000 8.0
3000 9.0
4000 10.0
5000 10.5
4. If proper ampere readings are not obtained, re-
place stator.
16 Ampere Stator
1. Check battery voltage at battery with engine
running.
2. If battery voltage is above 14.5 volts, replace volt-
age regulator/rectifier. Check condition of battery
as overcharging may damage battery.
3. If battery voltage is below 14.5 volts, charge bat-
tery; refer to “Charging a Discharged Battery”,
preceding. If battery can NOT be satisfactorily
charged, replace battery.
4. If battery accepts a satisfactory charge, check
battery voltage while cranking engine; refer to
“Charging a Discharged Battery”, preceding. If
cranking voltage is not acceptable, replace battery.
5. If cranking voltage is acceptable, disconnect
larger diameter RED harness wire from starter
solenoid terminal.

Mercury 90 Specifications

General

Brand	Mercury
Model	90
Category	Outboard Motor
Language	English