UanofCn 4-Stroke 9.9HP Outboard Marine Engine Parts

(1 products)

This page is for UanofCn 4-Stroke 9.9HP outboard engines. It helps you find compatible parts and service information, including maintenance tips, common replacement parts, and troubleshooting guidance. You can also browse the main Mercury collection. Scroll to the bottom of this page to start browsing parts for this engine. On the collection page, use the Filter & Sort controls to narrow results by horsepower, year range, and part category.

Browse All Mercury Parts

How to Identify Your 9.9HP Model

Nameplate/serial location: typically on the transom bracket or swivel bracket. Record the full model and serial number before ordering parts.
Model code and suffix: note shaft length (S=15, L=20), tiller vs. remote controls, and manual vs. electric start. These options affect certain parts (housings, harnesses, and controls).
4-stroke details: most 9.9HP 4-strokes in this class are twin-cylinder units. Earlier units are usually carbureted, while later versions may be EFI in some markets.
Platform clues: cooling-system parts (like the impeller) are often shared across 615HP families; always confirm by serial number when in doubt.

Engine Overview

9.9HP 4-Stroke Small Twin

Feature	Description
Configuration	Inline-2, 4-stroke, carbureted on earlier models; later variants may use electronic fuel injection. Air- or water-cooled oiling passages per 4-stroke architecture.
Common Models	General 9.9HP 4-stroke outboards in the small twin family (standard and long shaft, tiller or remote, manual or electric start).
Advantages	Quiet operation, good fuel economy, easy portability, and broad parts availability.
Notes	Many cooling-system components are shared across 615HP families. Certain parts differ by serial range, shaft length, and starting/controls. Verify by model & serial before purchase.

Routine Maintenance & Service Parts

Intervals below are general guidelines for small 4-stroke outboards. Always follow your official service manual and adjust for heavy use, sandy/silty water, or long storage periods.

Item	Interval*	Remarks	Parts Link
Engine oil & filter	100 hours or annually	Warm engine before draining; replace crush washer if equipped; use NMMA FC-W compliant oil.	Oil Filters
Gear oil (lower unit)	100 hours or annually	Change more often if water intrusion is suspected; inspect magnetic drain plug for metal.	Lower Unit Seal Kits
Spark plugs	Inspect 100 hours; replace 200 hours or as needed	Check gap and insulator color; replace if fouled or worn.	Spark Plug
Fuel filter (inline)	100 hours or annually	Replace sooner if storage or ethanol-related debris is present; use fresh stabilized fuel.	Fuel Filters
Water pump impeller / kit	Every 2 seasons (or 200 hours)	Replace more frequently in sandy/silty water or if tell-tale flow is weak.	Mercury Water Pump Repair Kits
Anodes (corrosion protection)	Inspect every service; replace when 50% consumed	Use the correct alloy (zinc, aluminum, or magnesium) for your water type.	Anodes

*Follow your engines service manual for exact intervals and procedures.

Frequently Used Parts Categories

Routine Service Service & Maintenance Kits
Cooling System Mercury Water Pump Repair Kits or Water Pump Impeller Rebuild Kits
Fuel System Fuel Filters
Ignition / Electrical Electrical Items and Spark Plug
Corrosion Protection Anodes
Gearcase & Propulsion Lower Unit Seal Kits and Propellers
Safety & Protection Propeller Guards

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Weak tell-tale stream or overheat alarm	Inspect intake screen for blockage; verify water pump impeller condition; check thermostat operation.	Water pump kit, thermostat, intake screen
Poor acceleration or power loss	Replace/inspect fuel filter; check spark plugs; confirm prop pitch/condition and for fishing line on the prop shaft.	Fuel filter, spark plugs, propeller
Hard starting or rough idle (warm or cold)	Confirm fresh, stabilized fuel; inspect/replace plugs; check primer bulb and fuel lines for air leaks.	Spark plugs, fuel filter, fuel hose/primer bulb
Gearcase noise or metal in gear oil	Inspect gear oil level/condition; pressure test for seal leaks; check for fishing line on prop shaft.	Lower unit seal kit, prop shaft seals, drain plug gaskets
Excessive smoke (4-stroke)	Verify oil level (not overfilled); check for rich mixture or flooded carb; inspect air intake path.	Spark plugs, air filter, carburetor components

FAQs

Are parts interchangeable across different years or platforms?

Some items are shared across the 615HP small-twin family, but many parts change by serial range, shaft length, and starting/controls. Always confirm with your exact model and serial.

When should I replace the impeller?

As a preventive measure, replace the impeller every 2 seasons (or about 200 hours). In sandy/silty water or if the tell-tale weakens, service sooner.

How often should I change the gear oil?

At least every 100 hours or once per season. If you see milky oil (water intrusion) or metal on the magnet, service immediately and pressure-test the gearcase.

What information do you need to verify compatibility?

Provide the full model and serial number, shaft length (S/L), tiller or remote controls, and whether its manual or electric start. Photos of the nameplate help ensure a correct match.

Ready to find what you need? Browse the main Mercury collection and narrow by horsepower, year, and model.

Shop Mercury Outboard Parts

If youre unsure about your model, send us a photo of the nameplate and the part you need and well help verify compatibility.