Boat Motor Maintenance

19 March 2011 On The Water

Maintenance of the boat motor is essential for keeping its operation safe and reliable. With so much of life at the lake dependent on the boat, take the time to follow these bits of advice.

Spring Boat Motor Checklist

Before you hop in the boat and race off to your favourite fishing spot on opening day, it is important to give the boat motor a thorough once-over.

Belts, Cables, Hoses

  • Look for damage such as cracks and splitting on the protective cover of the control cables.
  • Belts should not be loose.
  • Look for cracks, signs of wear, or weak spots on the belts.
  • Inspect the pulleys to make sure the belts are sitting properly.
  • Replace any faulty parts.

Fuel System

  • Look for loose or missing hose clamps.
  • Inspect the hoses for cracks or splitting.
  • Check connection points for signs of fuel leakage.
  • Make sure the prime bulb is not damaged.
  • Ensure the engine is running properly and the intake and exhaust points are clear of obstacles.

Water Pump

The water pump on the boat motor must be functioning properly.  Nothing will destroy your motor faster than running it at high RPM when the cooling system is not functioning.

  • Check the intake and exhaust points to ensure they are clear of obstacles.
  • Run the motor and check to see if the water flow is adequate and the water temperature is warm.

Note: If the water is too hot or the flow rate is low, do not run the motor.  There is a problem with the water pump or a blockage in the system.

Rule of Thumb: Change the water pump impeller every 2 or 3 seasons regardless of how much use the motor has had.  Sitting idle causes the impeller more damage than overuse.

Oil And Fuel

  • Only use new fuel.
  • Check the oil level and change the oil and filter if required. (4 stroke motors)
  • Check the power steering fluid and engine coolant if required.

Electrical System

  • Check the battery connections and charge level.
  • Ensure that all connections are attached securely.
  • Use steel wool to clean any signs of rust or corrosion.


  • Check the prop for any damage.
  • Ensure the pin is properly installed.
  • Test the bearings.  The prop should spin smoothly.

End Of Season And Winter Storage

During your last couple of boat runs, add some fuel conditioner into the gas tank to let it run all the way through the system.  This will help protect the motor as it sits through the winter.

Before you pull the boat out of the water, disconnect the fuel line to let the engine burn off the rest of the fuel that is in the carburetor. (Non oil-injected motors)

  • Remove the engine cover and inspect all hoses, clamps, etc. for damage or leaks.
  • Wipe down the entire area with a rag.
  • Spray WD-40 on all of the parts that move to keep everything fresh.
  • Spray fogging oil into the carburetor.
  • Disconnect the spark plugs.
  • Pull-start the engine a couple of times to let the fogging oil work its way into the system.
  • Change the oil and filter. (4 stroke motors)
  • Change the gear oil in the lower unit.
  • Cover the motor with a tarp to keep out the critters.

Note: Don’t store fuel over the winter.  Give it away, or use it in another motor.

Boat Motor Troubleshooting for Beginners

Boat motors have a lot of parts but there are a few simple things to check when a problem first arises.  Most of the time you can solve a simple issue yourself and avoid the inconvenience and expenses of taking the motor to a shop or buying a new one.

Problem: Motor Won’t Do Anything

  • Check the battery connections.
  • Check the battery charge.
  • Check the spark plug connections.
  • Remove and check the spark plugs. Clean the spark plug points with a piece of sandpaper.
  • Re-install the plugs and try to start the motor.
  • Replace the plugs with new ones.

Problem: Motor Will Spark But Not Start

  • Check the fuel line connection.  It must be connected correctly to both the tank and motor.
  • Check the fuel tank.  The vent must be open to allow air to enter the tank (external tanks).
  • Prime the fuel line. This brings fuel to the motor.
  • Pull the choke. This closes the plate that allows the air into the carburetor.  A higher fuel to air mixture improves starting conditions.

Problem: Motor Will Start But Quits Or Chugs Badly

  • Check the fuel tank for adequate fuel.
  • Check the choke. The choke lever must be pushed back in once the motor starts to allow air to flow into the carburetor.
  • Check for water in the fuel tank. Condensation will form in the tank and when mixed with the fuel will inhibit the operation of the motor.

How To Check For Water In The Fuel Tank?

  • Siphon the fuel into a clear plastic jug.
  • Let the old fuel sit for 20 minutes.  The water will settle to the bottom.
  • Siphon the clean fuel back out of the plastic jug, leaving only the settled water.
  • Place the water-free fuel back into the tank, or use fresh fuel.

Problem: The Boat Motor Dropped Into The Lake Or Became Fully Submerged.

  • Don’t try to start it!
  • Disconnect the battery.
  • Label the spark plug wires so you can reconnect them properly.
  • Disconnect the spark plugs.
  • Remove the spark plugs and dry them off.
  • With the plugs removed, pull-start the engine a few times to push the water out of the cylinders through the spark plug holes.
  • Let it air out and dry for a while.
  • Spray the park plug holes with fogging oil or Quick-Lube if you have it.
  • Replace the plugs, connect the plug wires, and connect the battery.
  • Cross your fingers and start the motor.  It make take a few tries before it starts.
  • Use a few squirts of Quick-Start in the carburetor if it needs a bit of help.

Note: Heavy rain will quickly fill an aluminum boat and sink it at the dock.  Remove the motor and battery from your aluminum fishing boat when a storm is forecast, especially if you do not plan to be at the cottage for a number of days.

Need more boat motor and boating tips?
Got to the Boat Motor Tilting Advice page.
Go to the Boat Trailer Maintenance page.
Go to the Spring and Fall Boat Maintenance page.