How to Troubleshoot Yamaha Boat Motors

by Brianna Collins
Yamaha's outboard lineup is designed to power personal watercraft.

Yamaha's outboard lineup is designed to power personal watercraft.

Over the years, the Yamaha Motor Corporation has released scores of outboard motors. Ranging from 2.5 horsepower to 300 horsepower and beyond, the company had over a dozen outboard makes in late 2010 alone. Like all mechanical devices, Yamaha outboards can experience problems in running or starting under certain conditions. Despite the great variety in engineering and power of its outboards, Yamaha recommends similar troubleshooting advice for most of its motor lineup based on specific problems.

Starter Won't Work

Verify that the shift lever is in neutral if the starter won't work.

Check the battery and its connections for any visible dirt and corrosion.

Tighten all battery connections with a wrench and socket. Clean the terminals with baking soda and a wire brush if they are dirty.

Replace the battery if the connections are corroded or appear damaged.

Try the starter again. Replace the fuses in the electric start relay or electric circuit if the starter still won't work.

Engine Won't Start

Verify that there is enough fuel in the fuel tank if the engine itself will not start. Refill with unleaded gasoline if the level is inadequate.

Empty the fuel tank and refill it with clean, fresh fuel if the gas is contaminated or old. Gummy or sticky residue in the fuel tank or along the fuel lines is an indication that the gas is old.

Check the condition of the fuel filter. Replace if it is clogged.

Inspect the spark plugs. Clean and replace them if the originals appear damaged or faulty.

Tighten all loose ignition wiring and replace any worn or broken wires.

Check the engine stop switch lanyard. Attach it if it is not already attached.

Engine Loses Power

Check the condition of the propeller if the engine starts but loses power. Replace or repair the propeller if it is damaged.

Adjust the trim to the recommended angle if the engine power has decreased.

Ensure that the motor is mounted at the correct transom height per the specifications in your owner's manual. Adjust the transom height, if it is incorrect, to ensure that the propeller operates effectively.

Check the bottom of the boat. Clean it if it is covered with marine growth as this can slow speeds.

Inspect the spark plugs and replace them if they are dirty or damaged.

Check the gear housing and clean it if debris has become lodged in the lower unit.

Verify that the fuel is not dirty or old. Replace if it if necessary.

Ensure that the correct kind of engine oil is being used for your particular outboard and fill to the recommended level.

Open the air vent screw if it is closed.

Engine Vibrates Excessively

Check the condition of the propeller if the engine is vibrating excessively. Replace or repair it as needed.

Inspect the propeller shaft and take it to a Yamaha dealer if it is damaged.

Clean the propeller of all weeds or other debris.

Tighten the motor mounting bolt.

Tighten the steering pivot. If it is damaged, have a Yamaha dealer replace it.

Items you will need

  • Fuse
  • Battery
  • Wrench
  • Socket set
  • Baking soda
  • Wire brush
  • Spark plug wrench
  • Spark plug(s)
  • Replacement propeller

Warnings

  • Do not smoke or work near an open flame when handling gasoline.
  • Wear gloves and eye protection, when working with batteries, to avoid burns.

About the Author

Brianna has been writing professionally since 2009. She has a Bachelor of Fine Arts degree and is excited to be part of a community that contributes to the free sharing of information and ideas.

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