Mercury – Fuel Line Assembly | Fuel System | Gray Low-Permeation Hose | 8M0078630

Overview

There’s something almost calming about that first squeeze of the primer bulb before you start the engine. When it firms up with that smooth, familiar pressure, you know your fuel is moving exactly the way it should. It’s a small gesture, but it sets the stage for the whole day — whether you’re slipping out at sunrise or riding home through a light chop. The Mercury Fuel Line Assembly 8M0078630 is built around that dependable, reassuring moment. It keeps fuel flowing steady and clean so you can stay focused on the water, not the line feeding your outboard.

Key Features

• Five-sixteenth-inch inside diameter hose delivers stable, consistent fuel flow
• Low-permeation hose construction helps preserve fuel quality and reduce odors
• Mercury-engineered primer bulb offers firm, predictable priming pressure
• Gray heat-reflective coating helps reduce vapor-lock risk in warm conditions
• Flexible, durable marine-grade hose built for long-term exposure
• Compatible with various tank and engine connector styles
• Ideal for portable tanks, built-in systems, and custom rigging layouts

Engine & Boat Compatibility

• Fits Mercury and Mariner outboards using a universal five-sixteenth-inch fuel line
• Works well with small to mid-range horsepower engines across many years
• Suitable for aluminum fishing boats, pontoons, skiffs, runabouts, tenders, and inflatables
• Adapts cleanly to different fuel tank types when paired with proper connectors

Performance & Practical Benefits

The difference is obvious from the first squeeze — the primer bulb tightens smoothly and evenly, giving you that confident signal that fuel is moving correctly. The hose routes naturally through tight rigging channels and bends around corners without kinking or collapsing, helping maintain uninterrupted flow even when the boat shifts through chop or passengers move around.

On warmer days, the gray exterior works quietly in your favor by reflecting heat instead of absorbing it. This helps keep fuel temperatures more stable and reduces the chances of vapor lock during long runs. The low-permeation design cuts down gasoline odor and slows fuel evaporation, especially helpful if your boat is stored under a cover or kept indoors. Over time, the hose stays flexible and resistant to cracking, while the primer bulb maintains that same crisp, reassuring firmness season after season. It all adds up to easier starts, cleaner idle, and fewer mid-season fuel issues.

Why Buy OEM

With fuel delivery, genuine Mercury Marine parts make a noticeable difference. Every component — from the hose blend to the internal check valves inside the primer bulb — is engineered specifically for marine use. Aftermarket assemblies might look similar, but they often fall short in durability, priming strength, or long-term reliability. Choosing OEM ensures proper fitment, consistent performance, and the peace of mind that comes from using parts designed for your outboard. It’s the practical choice for boaters who want gear that performs right the first time and keeps doing so.

FAQ

Q1: Which engines does the 8M0078630 Fuel Line Assembly fit?

It fits Mercury and Mariner outboards using a universal five-sixteenth-inch fuel line, once matched with the proper tank and engine connectors.

Q2: What makes this better than aftermarket options?

Stronger priming, better long-term hose flexibility, and Mercury-level durability and engineering.

Q3: How do I know it’s the right replacement?

Check that your setup uses a five-sixteenth-inch hose and identify the connector types you need. With the proper fittings, this assembly is typically a direct match.

Q4: Can it be used in both saltwater and freshwater?

Yes. It’s designed for reliable, long-term use in either environment.

Q5: Is installation straightforward?

Very. Add the correct connectors, route the hose cleanly, secure it properly, and most boaters can complete installation with ease.