2011 Yamaha F9.9FMSH Short Tiller – 4S (M16891)

2011 Yamaha F9.9FMSH Short Tiller – 4-Stroke (M16891) outboard motor is a compact, fuel-efficient, and reliable engine designed for small boats and versatile marine use. It is highly regarded for its quiet operation, clean emissions, and ease of handling. Below is a detailed description of this motor:

General Information

• Brand: Yamaha
• Model Year: 2011
• Horsepower: 9.9 HP
• Engine Type: 4-Stroke
• Control Type: Tiller Handle
• Shaft Length: Short (15 inches)
• Fuel Delivery: Carbureted

Key Features

• Lightweight and Compact: At approximately 87–100 pounds, it is easy to transport and install, making it perfect for small boats.
• Quiet Operation: The 4-stroke design ensures quieter performance compared to 2-stroke engines, with smooth idling and reduced vibration.
• Fuel Efficiency: Known for its excellent fuel economy, it is ideal for extended boating trips.
• Reliable Manual Start: Features an efficient pull-start system, ensuring dependable operation in all conditions.
• Durable and Corrosion-Resistant: Built to withstand freshwater and saltwater environments, with Yamaha’s proprietary anti-corrosion technology.

Fuel and Oil

• Fuel Type: Unleaded gasoline (minimum 87 octane).
• Oil Type: SAE 10W-30 or 10W-40 (Yamaha 4M or equivalent 4-stroke marine engine oil).
• Fuel Tank: Comes with an external fuel tank, typically 3 to 6 gallons.

Performance and Applications

• Top Speed: Typically reaches speeds of 10–15 mph, depending on boat size and load.

Applications:

• Dinghies
• Tenders
• Small fishing boats
• Utility boats
• Inflatable boats

Maintenance Tips

 Routine Oil Changes

• Change engine oil every 50 hours or once per season (whichever comes first).
• Use a Yamaha OEM oil filter for optimal performance.

Spark Plug Maintenance

• Recommended Spark Plug: NGK DPR6EA-9 or equivalent.
• Replace spark plugs annually or every 100 hours of operation.
• Check the gap, which should be set to 0.035 inches (0.9 mm).

 Cooling System Maintenance

• Inspect the water pump impeller and replace it every 2–3 years.
• Flush the engine with fresh water after use in saltwater to prevent corrosion and salt buildup.

Fuel System Care

• Replace the fuel filter annually to maintain clean fuel delivery.
• Use a fuel stabilizer such as Yamaha Fuel Med Rx when storing the motor for extended periods.
• Regularly inspect fuel lines for wear or leaks.

Gear Oil Change

• Change the lower unit gear oil annually or after 100 hours of operation.
• Use Yamaha marine gear oil for best results.

Common Issues and Troubleshooting

Hard Starting

• Cause: Stale fuel or dirty carburetor.
• Solution: Use fresh fuel, clean or rebuild the carburetor, and ensure the choke is functioning correctly.

Overheating

• Cause: Worn impeller or clogged cooling system.
• Solution: Replace the water pump impeller and ensure the cooling water intake is clear of debris.

Loss of Power

• Cause: Fouled spark plug or dirty fuel system.
• Solution: Replace spark plugs and clean the fuel system.

Parts and Accessories

OEM Parts

• Yamaha Dealers: Purchase genuine parts through authorized Yamaha dealers.
• Online Retailers:
  • YamahaOutboards.com
  • MarineEngine.com

Aftermarket Parts

• Sierra Marine: Offers high-quality aftermarket parts like fuel filters, impellers, and more.
• NGK Spark Plugs: Known for reliable performance in Yamaha outboards.

Used Parts

• eBay: Search for “2011 Yamaha F9.9FMSH parts” for used or refurbished components.
• Marine Salvage Yards: Often stock affordable parts for older motors.

Performance Enhancements

Propeller Upgrade:

• Standard aluminum props can be upgraded to stainless steel for improved performance and durability.
• Adjust the prop pitch for optimal speed or thrust based on your specific boating needs.

Fuel Optimization:

• Use ethanol-free gasoline whenever possible to prevent carburetor issues.
• Add a fuel stabilizer during storage to maintain fuel quality.

Periodic Tune-Ups:

• Decarbonize the engine to improve efficiency and reduce buildup.
• Regularly inspect and replace wear items like spark plugs and fuel lines. 2011 Yamaha F9.9FMSH Short Tiller – 4S (M16891)