Mercury 30 Service Manual

90-826148R2 MARCH 19972A-22 - ELECTRICAL
Ignition Diagnostic
Procedures
TROUBLESHOOTING TIP: With engine running,
use inductive timing light to check spark advance of
each cylinder as throttle is opened and closed. If tim-
ing advances and retards smoothly on each cylinder,
ignition system is MOST LIKELY functioning proper-
ly.
IMPORTANT: If outboard appears to have an igni-
tion system failure, it is recommended that be-
fore beginning in-depth troubleshooting:
a. Check ground leads on Timing Protection
Module, Capacitor Discharge Modules and
ground lead between ignition plate and en-
gine block for proper continuity.
b. Disconnect and reconnect ignition harness
connectors to verify proper continuity.
PROBLEM
CORRECTION
1. No Spark or Weak Spark on Both Cylinders No Spark - Trigger, Stator or Timing Protection
Module (TPM)
Weak Spark - Stator
2. No Spark or Weak Spark on 1 Cylinder Capacitor Discharge Module (CDM)
3. Timing Fluctuates - Note: It is normal for timing to
fluctuate 2°-3° @ Idle.
- If engine over-heats [above
190° F (88° C)], TPM will limit
engine RPM to 2500.
- If engine RPM exceeds 5800,
TPM will retard timing from 25
BTDC TO 14° BTDC.
- If RPM exceeds 6500 RPM,
TPM will momentarily shut
ignition off until RPM drops
below 6500.
- If engine RPM drops below
600, idle stabilizer in TPM will
advance timing to as high as
10° BTDC @ cranking speed
of 300 RPM.
Defective Engine Temperature Sensor
Defective TPM
4. Timing will not Advance on both Cylinders Defective TPM
5. Timing will not Advance on 1 Cylinder Check wiring between CDM and TPM. If wiring is
OK, replace CDM.
6. Engine Misfires @ High RPM Defective CDM
Defective TPM
7. Engine Hard to Start when Cold Defective Fuel Enrichment Valve
Defective TPM
8. Engine Misfires @ Low RPM but Runs Smooth @
High RPM
Defective Harness (loose connections) between
TPM and CDM
Defective CDM
Defective TPM
Defective Stator
9. Engine Starts Hard when Hot Defective TPM
10. Engine will not Run over 2500 RPM and is not
Over-Heating.
Defective Temperature Sensor
Defective TPM
11. Engine Occasionally Misfires Replace Standard Spark Plug with Inductor Plug

Mercury 30 Specifications

General

Horsepower	30 HP
Cylinders	3
Displacement	526 cc
Gear Shift	F-N-R
Fuel Induction System	Electronic Fuel Injection (EFI)
Shaft Length	20 in
Steering	Remote / Tiller