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Mercury Outboard Parts
Shop Mercury outboard motor parts by system, including cooling, fuel delivery, electrical, internal engine components, lower unit parts, and routine service items. Browse OEM and replacement Mercury marine parts to support maintenance, repair, and rebuild projects.
Shop by System
- Complete Powerheads
- Control Cables & Boxes
- Cooling System
- Cowlings & Components
- Electrical System
- Engine Oil
- Engine Rebuild Kits
- Fuel & Carburetion System
- Intake System
- Internal Engine Components
- Lower Unit Components
- Oiling System
- Paints
- Service & Oil Change Kits
- Service Manuals
- Steering Systems
- Throttle Components
- Transom & Midsection
- Trim System
- Wizard Performance Parts
Common Mercury Outboard Model References
This category supports many popular Mercury outboards across a wide horsepower range. Always confirm your model and serial number for best fitment.
- Portable & Midrange: 2.5HP–60HP (2-stroke & FourStroke)
- Performance: Pro XS and EFI platforms (75HP–300HP)
- Direct Injection: Optimax models (75HP–250HP)
- Premium Offshore: Verado models (135HP–400HP)
- Commercial: SeaPro models (commonly 75HP–300HP)
Always confirm your exact horsepower, model year, and serial number to ensure proper part compatibility before ordering.
20860
29816
30147
36288
54346
69792
70339
76039
760394
850307
78961
89594A1
8475252
Fits Mercury 75-250 HP DFI Outboards
Compatible with select Mercury 75-250 HP DFI outboard engines using injector #840481 and #804528. The Pro Marine 20-3071B Fuel Injector O-Ring is a replacement injector seal designed to maintain a proper seal around the fuel injector. It is associated with Manufacturer Item 804529 and is commonly searched by that number when replacing worn injector seals during fuel system service.
Compatibility
This injector O-ring is used on many Mercury DFI / Optimax outboards from 75 HP up to 250 HP. It is associated with OEM reference number 804529 and commonly used with fuel injectors 840481 and 804528.
Application Chart
Always confirm compatibility using your engine model, serial number, injector number, or existing part number before ordering.
Part Numbers & Cross References
| Reference Type | Part Number |
|---|---|
| Pro Marine Part | 20-3071B |
| Manufacturer Item | 804529 |
| Cross Reference # | 804529 |
| Fits Injector # | 840481 |
| Fits Injector # | 804528 |
What This Part Is Used For
Fuel injector O-rings help seal the injector properly when installed in the fuel rail or intake system. If an injector is removed for cleaning, inspection, or replacement, installing a new O-ring helps ensure the system seals correctly when reassembled.
Over time these seals can flatten, harden, or become damaged due to heat and fuel exposure. Replacing them during injector service helps prevent sealing issues and keeps fuel system maintenance reliable.
Frequently Asked Questions
What engines does this O-ring fit?
This part is listed for Mercury 75-250 HP DFI outboards and fits injector numbers 840481 and 804528.
What OEM number is associated with this part?
The product page lists both Manufacturer Item 804529 and Cross Reference #804529.
When should I replace a fuel injector O-ring?
Injector O-rings are commonly replaced anytime injectors are removed for cleaning, inspection, or replacement.
Is this an OEM Mercury part?
This listing is an aftermarket replacement part from Pro Marine associated with Mercury reference number 804529.
Dealer Discounts & Store Policies
Dealer / Marine Industry Discounts
Are you a marine dealer, technician, boat builder, or industry professional? We offer dealer pricing for qualified marine businesses.
Shipping Policy
- Free shipping on qualifying orders over $100 (continental U.S.).
- Orders ship via UPS, USPS, or FedEx.
- Orders received before 5:30 PM EST ship the same business day.
- Typical ground delivery time is 15 business days.
30-Day Return Policy
- Returns accepted within 30 days of delivery.
- Items must be new, unused, and in original packaging.
- Return authorization is required before sending items back.
Need help with a return or order question?
Contact Us
Phone: 941-721-3000
Searchable Part Numbers
Pro Marine Part: 20-3071B
Manufacturer Item: 804529
Cross Reference #: 804529
Fits Injector #: 840481, 804528
Common Search Terms: 20-3071B fuel injector o-ring, Mercury 804529, Mercury injector o-ring 804529, injector 840481 seal, injector 804528 o-ring