Sierra 18-7811

Enhance Your Outboard's Fuel System with the Sierra Diaphragm Kit

Keeping your marine engine running smoothly starts with reliable fuel delivery, and the diaphragm in your carburetor plays a critical role in that process. Over time, exposure to ethanol-blended fuels, heat, and constant vibration can cause diaphragms to harden, crack, or lose flexibility, leading to erratic performance on the water. The Sierra diaphragm kit steps in as a durable, precision-engineered solution designed to restore optimal function and get you back to enjoying hassle-free boating.

Crafted from high-quality, fuel-resistant materials, this kit ensures consistent metering of fuel and air mixtures, which directly impacts throttle response, idle stability, and overall power output. Boaters who upgrade to this replacement often notice sharper acceleration and fewer stalls, making it a smart choice for weekend warriors and serious anglers alike.

Perfect Fit for Popular Outboard Models

This diaphragm kit is engineered for seamless compatibility with a range of Mercury and Mariner outboard engines, particularly those in the popular 4-stroke and 2-stroke carbureted models. It matches the exact specifications of factory components, allowing for a drop-in replacement without modifications. Whether you're maintaining a classic workhorse or tuning up a reliable fishing rig, this kit aligns perfectly with engines from the 90s through early 2000s eras, ensuring broad applicability across your fleet.

• Direct OEM-spec replacement for enhanced reliability
• Fits multiple horsepower ranges for versatile use
• Resists degradation from modern fuel additives

Key Features That Stand Out

What sets this Sierra kit apart is its thoughtful design focused on longevity and ease of service. The diaphragm material flexes reliably under pressure, preventing leaks that could flood the engine or starve it of fuel. Included components are pre-cut and shaped for accuracy, reducing assembly time and minimizing errors during reinstallation.

Unlike generic alternatives, Sierra invests in materials tested for marine environments, where saltwater spray and humidity accelerate wear. This results in fewer rebuilds and more time on the water.

Spotting Diaphragm Failure Early

Don't wait for a breakdown to address carburetor issues. Common symptoms include hard starting, hesitation under load, black smoke from improper mixtures, or fuel dripping from the carb throat. A quick visual inspection—looking for tears, stiffness, or discoloration—can confirm the need for replacement. Regular checks during annual tune-ups can prevent these problems from escalating into costly repairs.

Simple Installation for DIY Boaters

Most boat owners with basic tools can handle this swap in under an hour per carburetor. Start by safely disconnecting the fuel line and removing the carburetor bowl. Gently extract the old diaphragm, clean the housing thoroughly, and install the new one, ensuring proper orientation to avoid binding. A dab of carb cleaner and fresh gasket sealer can make everything airtight. Always test-run on muffs before heading out to verify smooth operation.

1. Drain fuel and remove carburetor
2. Inspect and clean mating surfaces
3. Install new diaphragm and reassemble
4. Prime and test for leaks

Pro tip: Work in a well-ventilated area and wear gloves to handle fuel residues safely.

Maintenance Tips for Peak Performance

To maximize the lifespan of your new diaphragm, stabilize your fuel with an ethanol fighter and run the engine regularly to circulate fresh gas. Winterize properly by fogging carbs and storing dry. These habits can double the service interval compared to neglected systems, keeping your outboard primed for adventure.

Why Choose Sierra for Your Engine Parts?

Sierra has built a reputation for aftermarket excellence by reverse-engineering OEM designs with modern improvements. Their parts undergo rigorous testing for fit, form, and function, often outperforming originals in endurance trials. Boaters trust Sierra for value without compromising quality, making it the go-to for rebuilds and routine maintenance.