Sierra MP51090 3-Position Ignition Switch, Push to Choke, Replaces Mercury 87-17009A5

The Sierra MP51090 is a 3-position magneto ignition switch built for marine engines, covering the OFF-RUN-START sequence with a PUSH to Choke function for cold starts. It uses heavy duty potted construction to seal out moisture and vibration in the harsh marine environment, and is engineered with minimal bleed per circuit to keep electrical draw low across each contact path. The switch includes a molded umbrella type key, a durable design that resists the wear common to standard metal ignition keys on a boat's dash. Rated for 12 volt systems, it operates as a normally open, 3-way circuit switch with screw terminal connections for a secure wiring hookup, and is controlled by a push button actuator at the panel. The switch body is finished in white and built from polyester material with copper contacts, and it carries an IP54 ingress protection rating against dust and splashing water, an important spec for switches mounted on an open helm or console. It is designed for panel mounting and fits a standard 1 x 1 x 1 inch cutout footprint. This switch replaces Mercury outboard ignition switch 87-17009A5, making it a straightforward swap for boat owners repairing or upgrading a worn or failed OFF-RUN-START ignition switch on their console.

Specifications

• Brand: Sierra
• Manufacturer Part Number: MP51090
• Switch Type: Ignition Switch
• Positions: 3 Position Magneto - OFF-RUN-START
• Choke Function: Push to Choke
• Operating Voltage: 12 Volts
• Circuit Type: 3-way
• Contact Type: Normally Open
• Contact Material: Copper
• Connector Type: Screw Terminals
• Control Method: Push Button
• Actuator Type: Ignition
• Mounting Type: Panel Mount
• Construction: Heavy duty potted construction
• Key Type: Molded umbrella type key
• Ingress Protection Rating: IP54
• Color: White
• Material: Polyester
• Dimensions: 1 x 1 x 1 inches
• Weight: 0.3 pounds
• UPC: 808282269067

Fitment

Fits 12 volt marine ignition systems using a standard 1 x 1 x 1 inch panel-mount 3-position magneto switch.

Replaces (OEM)

• Mercury 87-17009A5

Frequently Asked Questions

What does the Sierra MP51090 replace? The MP51090 replaces Mercury ignition switch 87-17009A5, so it is a direct swap for that Mercury part.

How many positions does this ignition switch have? It is a 3-position magneto switch with OFF-RUN-START positions and a PUSH to Choke function for cold starts, part number MP51090.

What voltage is the MP51090 ignition switch rated for? 12 volts. The switch is built for standard 12 volt marine ignition circuits with a normally open, 3-way contact configuration.

What color is the MP51090 switch? White. The Sierra MP51090 ignition switch has a white finish designed to mount into a standard helm or dash panel.

What size cutout does the MP51090 need? The switch measures 1 x 1 x 1 inches, matching a standard panel-mount ignition switch cutout.

Is the MP51090 waterproof? It carries an IP54 ingress protection rating, meaning it is protected against dust and splashing water, and uses heavy duty potted construction to seal out moisture in the marine environment.

What material is the MP51090 switch made of? The switch body is made of polyester with copper contacts for reliable electrical conductivity.

How does the MP51090 connect to the wiring harness? It uses screw terminal connectors, allowing wires to be secured directly to the switch terminals rather than a plug connector.

What is the umbrella type key on the MP51090? The MP51090 includes a molded umbrella type key, a plastic-headed ignition key designed to hold up to repeated marine use better than a standard metal key.

How much does the MP51090 ignition switch weigh? The Sierra MP51090 weighs 0.3 pounds.

Does the MP51090 include a choke function? Yes, the MP51090 is a PUSH to Choke design, meaning pushing the key activates the choke circuit alongside the OFF-RUN-START positions.

What is the UPC for the Sierra MP51090? The Sierra MP51090 ignition switch is listed under UPC 808282269067.