Multi-Purpose Electronic Module (Mpem); Ignition Timing - Sea-doo 2003 XP DI Shop Manual

Section 12 ELECTRICAL SYSTEM
Subsection 02 (IGNITION SYSTEM (CARBURETED ENGINES))
787 RFI Engines
Crankshaft Position Sensor (CPS)
The CPS is an inductive speed sensor located on
the magneto housing and is working in conjunc-
tion with a 60 teeth ring gear which has 2 teeth
missing on the gear. The inductive sensor regis-
ters the 58-tooth sequence.
An AC voltage is generated by the sensor and is
sent to the ECU to calculate the crankshaft posi-
tion and the engine speed.
1
F07H0CA
1. Crankshaft position sensor (CPS)
Ignition Coil
Ignition coil induces voltage to a high level in sec-
ondary windings to produce a spark at spark plug.
GTI and GTI LE Models
The ignition coil steps up the voltage input from
the Multi-Purpose Electronic Module to high volt-
age current for both spark plugs.
The ignition coil is located in the rear electrical box-
located under air intake.
GTI LE RFI Models
The digital inductive ignition system on the RFI
models allows the spark plugs to spark indepen-
dently on each piston stroke.
CAUTION: Do not interchange spark plug ca-
bles. Reversed spark plug cables will not allow
the RFI to run and will cause backfires.
12-02-2
MULTI-PURPOSE ELECTRONIC
MODULE (MPEM)
717 and 787 RFI Engines
The MPEM is responsible of the following electri-
cal functions related to the ignition system:
– ignition timing curve
– engine rev limiter.
For the other functions of the MPEM, refer to IN-
STRUMENTS AND ACCESSORIES section.
787 RFI Engines
The MPEM is also used with the Rotax Fuel Injec-
tion system.
The RFI models use a Digital Inductive Ignition
system. The Bosch ECU controls the ignition tim-
ing and dwell time. It receives input from the CPS
and signals the ignition coil when to fire.

IGNITION TIMING

Before checking ignition timing with a stroboscop-
ic timing light (dynamic test), it is mandatory to
scribe a timing mark on the PTO flywheel (static
test) corresponding to the specific engine.
Also, the timing mark scribed on the PTO flywheel
can be used to troubleshoot a broken magneto
woodruff key.
CAUTION: The relation between the PTO fly-
wheel mark position and crankshaft position may
change as the PTO flywheel might move/tighten/
loosen on the crankshaft. As an example on
threaded flywheels, when the engine is accel-
erated out of water, PTO flywheel may tighten
then loosen when the engine is decelerated.
This will result in a false ignition timing read-
ing. Always verify PTO flywheel mark position
before checking ignition timing with an appro-
priate timing light. If mark does not align with
tool, repeat static test to ensure flywheel has
not loosen or moved before changing the igni-
tion timing.
NOTE: Do not use the factory mark found on the
PTO flywheel to check ignition timing or trouble-
shoot any problems.
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SMR2003-035_12_02A.FM