Page 136 - REPOWER REFERENCE GUIDE (2020)

Ignition System
Lubricants, Sealants, Adhesives

Tube Ref No. Description Where Used Part No.

25 Liquid Neoprene High tension wire coil tower 92- 25711 3
Ignition System Component Inspection

IMPORTANT: For timing procedures, refer to Section 8C: Ignition Timing.
Breaker Point Ignition Systems
Inspect the condition of all contacts to ensure continuity.
Distributor Sensor
• Visually inspect to ensure that there is no contact with the reluctor wheel.
• Inspect the condition of the wires.
• Check for continuity to ground.
Distributor Cap and Rotor
• Inspect the cap and rotor terminal for excessive burn and corrosion damage; clean, if possible.
• Inspect for carbon tracking in the cap; replace if any is found.
Distributor Housing Assembly
• Inspect breaker point lobes for excessive wear.
• Inspect the shaft for excessive lateral play, which indicates a worn shaft and bushings.
• Inspect the gear for excessive tooth wear and proper pattern.
Spark Plug Wires
• Inspect the condition of the wires for possible cracks in the boots and insulation.
• Check the continuity of the wires (ensuring that resistance values are within specification).
• Verify that the wires are routed correctly and are connected to the distributor in correct firing order.
Coil
• Visually inspect the coil for indication of carbon tracking on the coil tower. If carbon is found, replace the coil and the coil
wire.
• Verify that the primary and secondary winding resistance values are within specification.
Ignition Control Module

• Inspect for any indication of overheating.
• Inspect the connector terminals for corrosion.
Spark Plugs

• Verify that the plugs are correct for the application.
• Inspect for worn electrodes, and glazed, broken, or blistered porcelain.
• Inspect for proper gap.
Wiring Harness

• Inspect for chafing or melting of insulation.
• Verify continuity throughout the harness, checking for possible open circuits (using the wiggle test).
Spark Plug Inspection and Installation

Specifications

Mercury Part
Production Years Engine OEM Spark Plug Gap
Number
Prior to April 2006 Carbureted 5.0L (305 cid) and 5.7L (350 cid) AC Delco: 41‑932 33‑884019 1.14 mm
After April 2006 Carbureted 5.0L (305 cid) and 5.7L (350 cid) AC Delco: 41‑993 33‑884019001 (0.045 in.)

Page 5B-2 © 2019 Mercury Marine 90-8M0149179 eng NOVEMBER 2018