Fuel Injector Seal Kit – Fits Mercruiser/OMC Marine Engines (Replaces Prestolite 9-33303, Sierra 18-7696)

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Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This Fuel Injector Seal Kit is designed for Mercruiser and OMC marine applications, replacing old or damaged seals to prevent leaks and maintain correct engine performance. It ensures a proper seal for fuel injectors, which is crucial for fuel efficiency and engine reliability.

It serves as a direct replacement for Prestolite 9-33303, Mallory 9-33303, Sierra Marine 18-7696, and Walker Products 17056.

Engineered for direct-fit installation.
Constructed from high-temperature resistant materials to withstand engine bay heat.
Prevents fuel and air leakage around the injector for optimal fuel delivery.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number
Prestolite	9-33303
Mallory	9-33303
Sierra Marine	18-7696
Walker Products	17056

Technical Specs

Product Type: Fuel Injector Seal Kit
Installation: Direct replacement
Fuel Type: Compatible with gasoline marine engines
Housing Material: High-temperature resistant rubber or silicone
Dimensions: 4.0" L x 4.0" W x 1.0" H
Weight: 399 g (0.88 lb)
Other Technical Attributes: Prevents fuel and air leakage; ensures proper fuel delivery

Installation Notes

Disconnect the battery and relieve fuel system pressure to prevent fuel spray.
Carefully disconnect electrical connectors and remove any components obstructing access to the fuel rail.
Unbolt and gently remove the fuel rail assembly from the intake manifold.
Remove the old fuel injector seals, taking care not to damage the injector or seating surfaces.
Clean the injector ports and seating surfaces of any debris or residue.
Lubricate the new seals with clean engine oil or a suitable lubricant and install them onto the injectors.
Reinstall the fuel rail and injectors, ensuring they are seated correctly.
Torque the fuel rail bolts to the manufacturer’s specification.
Reconnect all electrical connectors and components.
Reconnect the battery, pressurize the fuel system, and carefully check for any leaks before starting the engine.

Troubleshooting & FAQ

How do I know if this seal kit fits my engine?

This kit is designed for a range of Mercruiser and OMC marine engines. The best way to confirm fitment is to match your existing part number to the ones listed in our Part Number Matrix: Prestolite 9-33303, Mallory 9-33303, Sierra Marine 18-7696, or Walker Products 17056.

What are the signs of a failing fuel injector seal?

Common symptoms include a strong smell of gasoline around the engine bay, visible fuel leakage near the injectors, poor engine performance, rough idling, hesitation during acceleration, and potentially a check engine light.

Can I replace just one seal, or should I replace all of them?

While you can replace a single leaking seal, it is highly recommended to replace all of them at the same time. The seals degrade at a similar rate due to heat and fuel exposure, so if one has failed, others are likely to fail soon.

Is any special lubricant needed for installation?

Applying a small amount of clean engine oil or a gasoline-safe lubricant to the new seals will help them slide into place without tearing or twisting, ensuring a proper seal.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.

Shipping speed & cost

We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns

Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.

Safety & Important Info

Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement, not an OEM component.
Professional installation is recommended for safety and performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.

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