Ignition Timing; Checking/Adjusting - Mercury MerCruiser MCM 454 Mag MPI Service Manual

SERVICE MANUAL NUMBER 23
INSTALLATION
1. Install coil bracket with coil to engine bracket using fasteners.
2. Connect high tension coil lead.
3. Connect wire harness connectors.

Ignition Timing

Checking/Adjusting

The engine must be at NORMAL OPERATING TEMPERATURE for this adjustment. Two
items of test equipment are required: an inductive pickup timing light and either a Scan Tool,
Diagnostic Code Tool, or MerCruiser Special Timing Tool (91-805747A1).
1. Connect timing light to number 1 ignition wire.
2. Connect the appropriate tool to the DLC connector of the wiring harness.
NOTE: The 7.4L MPI will automatically adjust engine to approximately 1200 - 1500 rpm
when put in the service or timing mode.
3. Manually adjust the engine throttle to 1800 rpm + 200.
4. If Not Using MerCruiser Timing Tool: With engine running, set the scan tool or Diag-
5. Shine the timing light at the timing mark indicator located on the timing chain cover.
NOTE: If adjustment is needed, loosen the distributor hold-down bolt and rotate the
distributor clockwise or counterclockwise to adjust the timing. Then repeat the timing light
check until the specification (8 degrees BTDC) is met.
6. Torque distributor hold-down bolt to 30 lb-ft (40 Nm).
7. Set Scan Tool or Diagnostic Code Tool to normal mode. If using the MerCruiser Special
8. Manually close throttle to bring engine down to idle state.
Index
90-861326--1 MARCH 1999
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a - Wire Harness Connection
b - High Tension Coil Lead Connection
nostic Code Tool to service mode.
a - Timing Marks
Timing Tool, disconnect it from DLC connector.
b
a
a
IGNITION SYSTEM
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