Sierra 18-7798 Fuel Pump Diaphram Kit

Keep your outboard motor running smoothly on every outing with a reliable fuel delivery system. A worn-out fuel pump diaphragm can lead to frustrating stalls, hard starts, or inconsistent performance right when you need it most—whether you're trolling for bass or cruising the open water. This kit steps in as the precise fix, restoring optimal fuel flow without the hassle of full pump replacement.

Why Your Fuel Pump Diaphragm Matters

The diaphragm acts as the heart of your fuel pump, flexing to draw fuel from the tank and push it to the carburetor or injectors. Over time, exposure to ethanol-blended fuels, heat, and constant vibration causes it to crack, harden, or swell. When that happens, air leaks in, starving your engine of fuel and risking dangerous breakdowns mid-trip. Replacing it promptly prevents bigger issues like fouled plugs or carburetor clogs, saving you time and towing fees.

Spotting the Signs of Diaphragm Failure

• Engine hesitates or bogs down under load
• Hard starting, especially after sitting
• Fuel smell near the motor or leaking primer bulb
• Inconsistent idle or black smoke from the exhaust
• Sudden power loss on plane

Catching these early keeps your adventures uninterrupted. A fresh diaphragm ensures consistent pressure, better throttle response, and peace of mind on longer runs.

Simple Swap for Peak Performance

Reviving your fuel pump doesn't require advanced tools or a shop visit. Start by disconnecting the battery and relieving fuel pressure—safety first to avoid spills or sparks. Remove the pump cover, swap the old diaphragm for the new one, inspect the check valves and gaskets included in the kit, then reassemble. Clean mating surfaces for a perfect seal, and test-run on the hose before hitting the water. Most boaters finish in under 30 minutes, breathing new life into their setup.

Pro tip: Flush the fuel system with fresh gas and stabilizer post-install to clear any debris. This maximizes longevity, especially with modern fuels that accelerate wear.

Built for Boaters, Backed by Quality

Engineered with marine-grade materials, this kit resists degradation from alcohol fuels and harsh saltwater environments. It flexes reliably through thousands of cycles, matching or exceeding factory specs for fit and function. Boaters rave about the instant improvement in starting ease and overall engine pep—no more guessing if fuel delivery is the culprit.

Long-Term Fuel System Care

Extend the life of your investment with these habits:

• Run the tank near empty before storage to minimize residue
• Use ethanol-free gas or quality stabilizers year-round
• Inspect lines and fittings annually for cracks
• Winterize properly to prevent fuel varnish

Pairing proactive maintenance with quality parts like this keeps downtime minimal and your boat ready for spontaneous launches.

Frequently Asked Questions