Mercury 225 EFI, Service Manual

Page: 82 / 719

IGNITION
Page 2A-26 90-884294 OCTOBER 2001
Symptom Cause Action
7. Speed Reduction (RPM
reduced) 7.1 Low battery voltage
ECM requires 8 volts mini-
mum
Fuel Pump requires 9 volts
Check battery and/or alternator.
Check electrical connections.
7.2 Overheat condition Check water pump impeller/cooling
system.
7.3 Oil pump electrical failure Check electrical connection.
7.4 TPS failure
If TPS fails, rpm is reduced
to idle
See 2.2
8. Engine RPM reduced to
idle only 8.1 TPS failed
8.2 Battery voltage below 9.5
volts
See 2.2
Use DDT to monitor system
9. Loss of spark on 1 cylin-
der 9.1 Loose wire or pin in connec-
tors between ECM and coil pri-
mary.
9.2 Faulty ignition coil.
9.3 Faulty spark plug.
9.4 Faulty spark plug wire
Note: If spark plug is partially
fouled or the plug gap is too
small, the DDT may indicate the
incorrect cylinder as having an
ignition fault. Example: If the
DDT indicates an ignition fault
on cylinder #4, the problem may
be on the prior cylinder in the
firing order – I.E. cylinder num-
ber #3.
Check connectors.
Replace coil.
Replace spark plug.
Replace spark plug wire.