In the high-stakes world of Mercury Racing two-stroke EFI outboards, every component matters—especially the pintle caps on the legendary Bosch-style fuel injectors.
 
If you’re running a 2.0L F1, 2.4L EFI, 2.5L EFI Offshore, Bridgeport, 260/280 ROS, 300 Drag, or S3000 powerhead, you already know the story: the original Mercury part numbers 98818 and 988181 (sometimes cross-referenced as 8M0192275) are now No Longer Available (NLA) from the factory.
 
When it’s time to service these injectors, one of the most common wear items is the pintle cap—the small, precision-molded plastic cap that protects the delicate pintle valve and shapes the critical fuel spray pattern.
 
Why Pintle Caps Matter in Mercury Racing Applications
 
These injectors are hose-feed, pintle-style Bosch units (commonly identified as EV1-type bodies) mounted directly into the aluminum fuel rails of high-RPM marine engines. The pintle cap:
 
Directs the fuel into the optimal conical or multi-hole spray pattern for efficient atomization in the crankcase or intake tract.
Shields the pintle from debris, vibration, and thermal cycling.
Maintains consistent flow and prevents fuel dribble that can cause lean spots, detonation, or fouled plugs at wide-open throttle.
 
In harsh marine environments—ethanol-blended fuel, saltwater exposure, high vibration, and sustained high-RPM operation—the original caps become brittle, crack, or lose their retaining lip over time.
 
A damaged or missing cap leads to poor atomization, uneven cylinder fueling, rough idle, hesitation, and potential engine damage.
 
Our Precision Replacement Pintle Caps – Engineered for Exact OEM Fit and Performance
Our replacement pintle caps are manufactured to the exact dimensional specifications of the original Mercury/Bosch design:
 
Inner diameter and retention lip: Snug, positive snap-fit over the injector nozzle
Discharge orifice: 1.5 mm precision hole (standard for these injectors) to preserve the factory spray pattern and flow rate.
Material: High-temperature, fuel-resistant engineering polymer that resists ethanol degradation, cracking, and heat soak far better than aged OEM caps.
Color-coded for easy identification: Matches the later OEM original appearance for quick visual inspection during service.
 
Available in a convenient 6-pack, to refresh all injectors.
 
These caps are fully compatible with both 98818 and 988181 injectors and the aftermarket high-flow direct replacements now offered by specialty marine suppliers.
 
Restores factory spray quality – Critical for maintaining proper air/fuel ratios in these high-output EFI two-strokes.
Prevents lean conditions – Especially important on 280+ HP Offshore and Drag setups where every millisecond of injector pulse width counts.
Cost-effective maintenance – Instead of chasing rare NLA OEM injectors or full replacements, a simple cap (plus O-ring and filter basket) refresh can bring tired injectors back to spec when combined with professional ultrasonic cleaning and flow-testing.
Proven in the field – Used by top Mercury Racing builders, offshore racers, and performance shops who demand repeatable results.
 
Professional Installation Tips for Mercury Racing Injectors
 
Depressurize and remove – Always relieve fuel pressure and disconnect the battery.
Removal – Use a thin razor blade or pick to cut and peel the old cap and lower O-ring. A small socket or dedicated relief tool works well to pry evenly without stressing the pintle.
Clean thoroughly – Ultrasonically clean the injector body and inspect the pintle for wear or scoring.
Press-on – Warm the cap slightly with a heat gun or hair dryer for pliability. Use a right-sized socket or relief tool that clears the pintle tip and apply firm, even pressure until it snaps securely.
Flow test – Always verify spray pattern and flow match after reassembly (highly recommended before reinstalling in the powerhead).
 
Pro tip: While the injectors themselves are generally not “rebuildable” in the traditional sense (no internal pintle or spring kits), replacing the pintle cap, top filter screen, and all O-rings is the accepted best-practice refresh for these Bosch marine units.
 
Keep Your Mercury Racing EFI Running Strong
 
Don’t let a worn pintle cap be the weak link in your fuel system. Our direct-fit replacement caps give you an affordable, reliable way to maintain peak performance and protect your investment in these iconic high-performance outboards.
 
Whether you’re a weekend offshore angler, a competitive drag racer, or a professional engine builder, these caps deliver OEM-level quality at a fraction of the cost of chasing discontinued factory parts.