Professionally Cleaned & Flow-Tested Opti Injectors by Buckshot Racing #77
The Mercury OEM Fuel Injector Assembly 804528, also referenced as 8M0222157, is a key fuel-metering component used across many Mercury DFI Optimax outboards. This injector appears in 1.5 Liter three-cylinder Optimax engines, 2.5 Liter Pro XS and Sport XS models, 3.0 Liter V6 DFI outboards, and 3.2 Liter 300XS performance applications.
On a Mercury Optimax, the injector is part of a precise direct fuel injection system that depends on accurate fuel volume, clean spray behavior, proper fuel pressure, correct air pressure, and balanced delivery across all cylinders. When the injector performs correctly, the engine idles cleaner, accelerates harder, maintains better fuel control, and helps protect the powerhead from lean-running damage.
What This Fuel Injector Does
Mercury Optimax engines use an air-assisted direct fuel injection system. The 804528 / 8M0222157 fuel injector meters gasoline into the system, while the compressor-supported air side helps atomize and deliver the charge into the combustion chamber. Because fuel pressure and air pressure work together, injector condition directly affects combustion quality.
On performance models such as the 250 HP Pro XS, 250XS, 250 Sport XS, and 300XS 3.2L, consistent injector output is especially important. These engines are often operated under heavy load, where a restricted or uneven injector can cause rough running, hesitation, elevated piston temperature, poor fuel economy, or serious engine damage.
Symptoms of a Bad or Restricted Optimax Fuel Injector
A contaminated Opti injector may still click electrically but fail to flow correctly. Varnish, ethanol residue, old fuel, water contamination, fuel hose debris, and dirty rails can all affect injector performance.
Common symptoms include hard starting, rough idle, lean sneeze, hesitation, weak throttle response, reduced top-end RPM, misfire codes, excessive smoke, uneven spark plug color, fuel economy changes, or one cylinder running hotter than the others. These issues are often mistaken for ignition, reed, compressor, or ECM problems when the real cause is poor injector fuel delivery.
Broad Mercury DFI and Opti Fitment
The Mercury 804528 / 8M0222157 fuel injector assembly fits many Mercury DFI Optimax applications, including 75 HP 3-cylinder 1.5L, 90 HP 3-cylinder 1.5L, 115 HP 3-cylinder 1.5L, 115 HP Pro XS 1.5L, and 125 HP 3-cylinder 1.5L outboards.
It is also used on many V6 DFI models, including 150 HP Pro XS 2.5L, 175 HP Pro XS 2.5L, 200 HP 3.0L, 200 HP DTS 3.0L, 200 HP Pro XS 3.0L, 200 HP XS 2.5L, 200 HP XS ROS, and 200 HP XS SST engines.
Additional applications include 225 HP 3.0L, 225 HP XS 2.5L, 250 HP 3.0L, 250 HP Pro XS 3.0L, 250 HP Sport XS 2.5L, 250 HP XS 3.0L, and 300 HP XS 3.2L / 300XS Mercury Optimax performance outboards.
This injector is also found in Mercury Jet Drive and SportJet DFI applications, including 200 DFI Jet Drive, 200 DFI M2 Jet Drive, 250 DFI Jet Drive, 250 DFI M2 Jet Drive, and select JP 3.0L models. Because Mercury used this injector across multiple serial-number ranges, always verify fitment by engine serial number before ordering.
Why OEM Fuel Injector Quality Matters
The Optimax platform is sensitive to fuel delivery accuracy. A poor-quality injector, unknown used injector, or a mismatched injector set can create problems that are difficult to diagnose. Proper injector performance is just as important as compression, spark, fuel pressure, air pressure, reed condition, and clean fuel supply.
When replacing an injector, inspect the surrounding fuel system. Contaminated rails, weak fuel pumps, deteriorated hoses, clogged filters, water in the tank, or a restricted vapor separator can quickly damage a replacement injector or cause the same running issue to return.
Buckshot Racing #77 Injector Standards
Buckshot Racing #77 supplies used OEM Mercury 804528 / 8M0222157 fuel injectors for Optimax DFI applications. These are genuine Mercury injector assemblies designed for the 1.5L, 2.5L, 3.0L, and 3.2L Optimax fuel system.
Our used OEM injectors are cleaned, inspected, rebuilt as needed, and flow-tested before sale. The main value is using the correct Mercury injector for the correct Optimax application, with professional verification before it goes back into service.
Final Thoughts
The Mercury OEM 804528 / 8M0222157 Fuel Injector Assembly is an essential part of the Optimax DFI fuel system. Whether repairing a 75 HP 1.5L Optimax, maintaining a 200 HP Pro XS, rebuilding a 250 Sport XS, servicing a 250XS, or keeping a 300XS 3.2L running strong, the correct injector is critical to fuel delivery, engine protection, and long-term reliability.