Mercury 40 FourStroke - Page 91

IGNITION
Page 2A-16 90-857046R1 NOVEMBER 2001
*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.
Engine Misfires At High RPM
Low Oil Pressure/Engine Over Heating:
a - timing retards and fluctuates, rpm
will remain below 2000 rpm
Ignition Coil/High Tension Lead(s)
Spark Plug Cap(s)
Spark Plug(s)
(ECM) Unit
Ground Connection:
a - (ECM)
b - ignition coil
c - stator
4
2
2
3
3
3
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
4
Engine Will Not Run Over 2000 RPM Low Oil Pressure/Engine Over Heating:
a - timing retards and fluctuates, rpm
will remain below 2000 rpm
Stator
Ignition Coil/High Tension Lead(s)
(ECM)
Spark Plug(s)
4
1-2
2
3
3
Engine Occasionally Misfires Charge Coil
Ignition Coil/High Tension Lead(s)
Spark Plug Cap(s)
Spark Plug(s)
Ground Connection at:
a - ignition coil
b - (ECM)
c - stator
High Resistance To Ground at:
a - stop/lanyard switch (water/corro-
sion)
(ECM)
1-2
2
2
3
2
3
2
2
3
Engine Surges Over
6200 RPM While Under Load
NOTE: The engine (ECM)
will retard timing and
reduce RPM above 6200
RPM.
Boat Under Propped
Propeller Hub Spun
4
4