Sierra 18-99270 CDM Inductive Spark Plug Wire, 11.5 Inch, Single Booted, for Mercury Outboard Engines

The Sierra 18-99270 is a single-booted CDM inductive spark plug wire measuring 11.5 inches, built for Mercury outboard engines that use inductive-type ignition components. It is designed as a direct replacement for a worn, cracked, or arcing spark plug wire, delivering the ignition spark from the powerhead's ignition system to the spark plug so the cylinder fires reliably. The single boot on the wire seats over the spark plug terminal to maintain a secure, weather-resistant connection in the engine compartment.

A degraded spark plug wire is a common cause of misfires, hard starting, and rough idle in outboard motors, and replacing it with a properly sized, application-specific wire like the 18-99270 helps restore consistent spark delivery. At 0.11 pounds, this is a lightweight, single-cylinder wire intended to be matched to the correct position on a Mercury outboard powerhead using CDM inductive ignition.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-99270
• Product Name: CDM Inductive Spark Plug Wire, Single Booted
• Length: 11.5 inches
• Boot Configuration: Single booted
• Ignition Type: CDM inductive
• Weight: 0.11 pounds
• UPC: 808282395162

Fitment

• Mercury outboard engines using CDM inductive ignition

Replaces (OEM)

• No OEM cross-reference numbers available

Frequently Asked Questions

What is the Sierra 18-99270 spark plug wire used for? The Sierra 18-99270 is a single-booted CDM inductive spark plug wire that carries ignition spark from a Mercury outboard's ignition system to the spark plug, used to replace a worn or damaged wire on the powerhead.

How long is the 18-99270 spark plug wire? It measures 11.5 inches in length.

Does the 18-99270 wire have one boot or two? The 18-99270 is a single-booted wire, with one boot that seats over the spark plug terminal.

What type of ignition system is the 18-99270 designed for? This wire is built for CDM inductive ignition systems, as used on compatible Mercury outboard engines.

How much does the Sierra 18-99270 weigh? The 18-99270 spark plug wire weighs 0.11 pounds.

Is the Sierra 18-99270 a genuine Sierra part? Yes, 18-99270 is the Sierra manufacturer part number for this CDM inductive spark plug wire.

Will the 18-99270 fit any outboard brand? The 18-99270 CDM inductive spark plug wire is designed for Mercury outboard engines that use CDM inductive ignition.

What signs indicate a spark plug wire like the 18-99270 needs replacing? Misfires, hard starting, and rough idle can point to a degraded spark plug wire, and replacing it with a correctly fitted wire such as the 18-99270 helps restore consistent spark delivery.

What is included with the Sierra 18-99270? The 18-99270 is supplied as a single spark plug wire with its boot attached, ready to install on the applicable cylinder position.

Can the 18-99270 be used as a single-cylinder replacement rather than a full set? Yes, the 18-99270 is sold as an individual 11.5 inch single-booted wire, allowing replacement of just the affected cylinder's wire rather than an entire ignition harness.