Sierra Marine Fuel Pump 18-7278 – Mercury / Mariner 4HP-15HP 2-Stroke Fuel Delivery Pump
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
The Sierra 18-7278 Fuel Pump is a diaphragm-style fuel pump designed to deliver consistent fuel flow in small horsepower Mercury and Mariner 2-stroke outboards. This pump ensures proper fuel transfer from the tank to the carburetor, supporting smooth engine operation and reliable performance.
Engineered to meet or exceed OEM specifications, this pump is a direct replacement for worn or failing units and is ideal for restoring proper fuel pressure in portable outboard applications.
Perfect for resolving hard starting, fuel starvation, or inconsistent idle performance.
Key Features
- Diaphragm-style fuel pump assembly
- Designed for small horsepower outboards
- Provides consistent fuel delivery and pressure
- Direct OEM replacement fit and function
- Marine-grade construction for durability
- Sierra limited lifetime warranty
Engine Compatibility
Mercury / Mariner Outboards (2-Stroke)
- 4 HP
- 5 HP
- 6 HP
- 7.5 HP
- 8 HP
- 9.9 HP
- 15 HP
➡️ Fits a wide range of portable Mercury/Mariner 2-stroke engines
Serial Number Fitment Notice
Fitment varies depending on carburetor configuration and fuel system design.
⚠️ Always confirm:
- Engine serial number
- Mounting configuration
- Fuel line routing and pulse port setup
Some models may use different pump styles depending on production year.
When This Part Needs Replacement
Replace the fuel pump if you notice:
- Hard starting or extended cranking
- Engine bogging or hesitation
- Fuel starvation at higher RPM
- Poor idle quality
- Fuel leaks or diaphragm failure
Installation Notes
- Ensure pulse line is properly connected and not cracked
- Inspect fuel lines and primer bulb during installation
- Replace mounting gasket if required
- Check carburetor condition after installation
- Verify no air leaks in fuel system
Alternate / Superseded Part Numbers
OEM Cross References
- Mercury / Mariner:
- 803529T
- 803529T1
- 803529A1
Aftermarket Cross References
- Mallory: 9-35350
- GLM: 40520
Shipping
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.