SeaSierra 5/16" (8mm) Outboard Primer Bulb – Universal Rubber Fuel Line Pump, Inline Replacement

The SeaSierra 5/16" (8mm) outboard universal rubber primer bulb is a simple, durable hand-pump that moves fuel from tank to engine for easier cold starts and reliable fuel delivery.

When you need to prime a small outboard motor, this compact rubber primer bulb supplies a quick, tool-free way to transfer fuel and remove air from the line. Built to fit common outboard brands and sized for a 5/16" (8mm) inner-diameter hose, the SeaSierra primer bulb is a practical replacement part for aging or damaged fuel connectors. It installs inline between the tank and engine, offering a user-friendly method to restore fuel flow before cranking.

What engines and hoses will this SeaSierra primer bulb work with?

This primer bulb is made to be broadly compatible with many popular outboard makes, including Yamaha, Tohatsu, Mercury, Mariner, Johnson, Evinrude, OMC and Honda. The critical dimension is the inner hose diameter: it is sized for 5/16" (8mm) fuel hoses. Many marine fuel hoses and stock outboard connector lines use this common size, making the bulb a versatile replacement.

• Fits 5/16" (8mm) inner-diameter fuel hoses
• Compatible with major outboard brands for tank-to-engine connections
• Designed as a direct inline replacement for worn primer bulbs
• Works with standard marine fuel hose materials used on small outboards

How do I install and use the primer bulb?

Installation is straightforward: cut the fuel line where you need the bulb, slide hose clamps on, push the hose ends onto the bulb’s tapered fittings, then tighten clamps. To prime, squeeze the bulb several times to draw fuel through and purge air; once steady fuel appears, the engine is ready to start. No special tools are required beyond a hose cutter and clamps.

• Cut hose squarely to prevent leaks
• Use clamps rated for marine fuel systems
• Squeeze bulb until fuel flow is consistent and free of air
• Check for leaks after installation and before starting engine

What are the material and care considerations for this rubber primer bulb?

The SeaSierra bulb is molded from fuel-resistant rubber designed to handle gasoline and typical marine fuel blends, but like all rubber parts it is sensitive to long-term UV exposure and harsh storage conditions. Avoid leaving it in direct sunlight for extended periods and store in a cool, shaded area when not in use to extend service life. Inspect periodically for cracking, stiffness or leaks and replace if any deterioration appears.

• Made of fuel-resistant rubber for marine use
• Keep out of prolonged direct sunlight to prevent hardening
• Inspect seals, fittings and body for cracks or softness
• Replace if fuel odor, swelling, or seepage is detected

How does this primer bulb improve starting and performance?

By manually transferring fuel and eliminating air pockets in the line, the primer bulb helps ensure the carburetor or fuel-injection system receives a steady supply of fuel during startup. That reduces cranking time and misfires associated with air-bound fuel lines. While not a performance enhancer, it reliably restores proper fuel flow for dependable engine starts.

• Removes air pockets for consistent fuel delivery
• Speeds up cold starts by pre-filling fuel lines
• Prevents dry-cranking that stresses starter systems
• Useful as an emergency repair or routine maintenance part

Who is this for: The SeaSierra 5/16" (8mm) universal rubber primer bulb is aimed at boat owners, marine mechanics and anglers who run small outboard motors and need a dependable inline priming solution. It’s ideal for anyone maintaining older boats, replacing brittle or leaking primer bulbs, or keeping a spare on board for quick field repairs. If your outboard uses 5/16" fuel hose and you want a low-cost, easy-to-install replacement that restores reliable fuel flow, this SeaSierra primer bulb is a practical choice.