Mercury 40

IGNITION
Page 2A-14 90-828631R3 MARCH 1999
Weak Spark Condition
(Low Primary Voltage)
Ground Connection at:
a - ignition coil
b - (CDI) unit
c - stator
High Resistance To Ground at:
a - stop/lanyard switch (water/corrosion)
Weak Charge Coil
(CDI) Unit Failure
Ignition Coil/High Tension Lead(s)
Spark Plug(s)
Spark Plug Cap (Resistor)
2
2
2
2
1-2
1-3
2
3
2
Timing Fluctuates
Note: It is considered normal for the timing
to fluctuate approximately 1° - 2° within the
designated timing window.
Loss Of Oil Pressure:
a - timing retards and fluctuates, rpm will
drop below 2000 rpm
Flywheel Key Sheared
(CDI) Unit
4
4
3
*Recommended Test (cont.)
(1) DVA TEST (Direct Voltage Adapter)
(2) OHM TEST (Resistance Testing)
(3) Replace Component and Retest
(4) Mechanical Test/Repair
PROBLEM/CONDITION
Probable Cause *Perform
Test No.
Timing Will Not Advance Low Oil Pressure:
a - timing retards and fluctuates, rpm
will remain below 2000 rpm
(CDI) Unit
4
1-3
Engine Misfires At High RPM
Low Oil Pressure:
a - timing retards and fluctuates, rpm
will remain below 2000 rpm
Ignition Coil/High Tension Lead(s)
Spark Plug Cap(s) 5k Ω Resistor
Spark Plug(s)
(CDI) Unit
Ground Connection:
a - (CDI) unit
b - ignition coil
c - stator
4
2
2
3
1-3
2
2
2
Engine Hard To Start Cold Debris In Carburetor Enrichener Circuit
Weak Spark Condition
Throttle Plate in Open Position
4
1
4
Engine Hard To Start Hot Weak Spark Condition
Vapor Lock
4
1
Engine Will Not Run Over 2000 RPM Low Oil Pressure
a - timing retards and fluctuates, rpm
will remain below 2000 rpm
Stator
Ignition Coil/High Tension Lead(s)
(CDI) Unit
Spark Plug(s)
4
1-2
2
1-3
3