The Most Common Outboard Motor Problems

As we head into warmer weather, it’s time again for boating. It’s great to head out on the water with friends and family to enjoy some time out in nature. It’s not so great, though, if your boat’s outboard motor develops issues. Here are a few common problems you might have with the outboard motor on your boat.

Older outboard motors are harder to start

Motors that are 20 or 30 years old are usually still reliable, says However, they weren’t designed with today’s electronics, so they aren’t able to generate as strong a spark to cause combustion. Also, for two-stroke motors, points out that the oil must often “be pre-mixed with the fuel in the tank.”

Older motors can also be harder to start when they don’t have modern fuel injection systems or automatic chokes. The operating manual for the motor can provide some guidance on the best ways to start these older motors.

In general, suggests moving the throttle to the start position, turning on the fuel, and opening the vent for the tank. For a remote tank, squeeze the bulb in the fuel line a few times. Pull and release the start cord from a reasonable distance, and then turn the choke to the running position. That will be for just a few seconds for a two-stroke motor and 10 to 20 seconds for a small four-stroke motor. If the motor just won’t start, the battery could be dead, or there could be an ignition circuit problem.

Ethanol-blended fuel problems

Fuel systems that use ethanol-blended fuel can experience issues like sputtering or losing power if the fuel goes bad. To avoid this, recommends using a high-quality 10-micron fuel/water separating filter to keep water out of the outboard motor. It’s good to have a spare filter on board as well.

Boating Magazine says to “remember to vent the engine box thoroughly before restarting” after a new filter is installed. Also, include a high-quality fuel stabilizer each time fuel is added to the boat to help prevent fuel from going bad in the boat.

Carburetor build-up issues

Older two-stroke outboard motors are prone to build-up in the carburetor. The fuel, when mixed with two-stroke oil, only lasts for a few months. As the fuel evaporates, it leaves a build-up inside the carburetor, restricting the amount of fuel the motor can get. When this happens, the motor starts to misfire and run roughly or lose power. It will run a little better if given choke, but that will only be a temporary solution to get the boat to dock.

To avoid this problem, use the boat weekly to keep the carburetor wet or squeeze the priming bulb weekly several times to wet the carburetor without turning on the motor. Adding fuel stabilizer will also help the fuel to last longer.

Another way to avoid the problem is to drain the fuel from the carburetor after finishing with the boat for the week. The operating manual will show the best way to do this for that particular motor. If problems do occur, the carburetor will need to be removed so the jets can be cleaned.

The outboard motor starts to overheat

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Outboard motors cool themselves with the water the boat is riding on. They don’t have radiators the way cars do. Usually, says Boating Magazine, this problem is caused by something blocking the water intake valve. It could be mud, plants, or trash, and this debris should be cleaned out of the motor. It’s helpful to have wire onboard to help with this cleaning. There could also be a loose or broken hose or clamp that will need to be repaired. The motor should have regular maintenance that checks the impeller and the exhaust system.

While modern outboard motors are quite reliable and maintaining your motor will help ensure that, there are still issues that can pop up. It’s important to pay special attention to the motor’s fuel system since that’s often a common culprit behind many issues. Here’s to a summer free of outboard motor problems.