Becoming a Motor Whisperer: How to Coax a Finicky 2-Stroke Outboard to Start

2 Stroke Outboard Motor Won't Start

Few things are more frustrating than getting everything ready for a much-anticipated stint of fishing or boating, only to discover that your outboard motor won’t start. After all, having the freedom to get out on the water whenever the mood strikes is one of the main reasons most people purchase a boat. We may not like it, but the fact is, boats and motors can be finicky, especially if you purchase an older model. To minimize frustration and maximize fun, get a boat history report before you buy, and make sure you know how to diagnose and troubleshoot problems that could be keeping your motor from starting and running correctly.

Understanding the Basics: How Outboard Motors Work

Much like your car’s engine, your outboard motor produces energy (and movement) by igniting gas and oxygen inside its cylinders. In your car, these tiny explosions cause pistons inside the cylinders to push the crank around the crankshaft, transferring power to the wheels. Your outboard motor has many of the same parts and functions in much the same way, except that the cylinders are smaller, and the motor transfers its power to the propeller instead of a set of wheels. If your motor is a “2-stroke,” it has two cylinders, but motors also come in a “4-stroke” configuration.

A flywheel sits at the top of the motor, and as it spins, it builds up momentum, which helps the engine maintain a steady speed. There’s also a carburetor, which controls the mixture of oxygen and gasoline in the cylinders; a fuel pump, which sends gas to the carburetor; and a camshaft, which opens and closes the cylinder valves to let fuel in and exhaust gases out. Spark plugs ignite the fuel in the cylinders, and as the pistons move in and out, driveshaft transfers power from the crankshaft to the gearbox, which makes the propeller rotate. The throttle controls how fast the engine rotates, how much power it produces, and how fast the boat goes.

From its invention in 1906 until the 1930s, outboard motors were designed to start via a pull cord: yanking on a thick line wrapped around the end of the crankshaft causes it to rotate, engaging the flywheel and enabling the motor to start. However, newer outboard motors have an electric start which is powered by a battery.

Finally, most outboard motors are mounted so that you can adjust their angle and direction. Tilting the motor back toward you raises the propeller out of the water, which is important if you’re in a shallow area or there’s debris that could damage it. Turning it left or right allows you to change the direction of the boat.

Motor Won’t Start? Check These Things

First and foremost, make sure you have plenty of gas. It may sound obvious, but the fuel level is easy to check, and it’s one of the most common explanations for a motor that won’t start. Additionally, double-check that the fuel shutoff valve is set to “on” – otherwise gas won’t reach the motor, no matter how full your tank is.

If you have an external fuel tank, make sure the fuel line is properly connected to both the tank and the engine. Tug on the line to make sure it’s snuggly attached on either end and use a flat-head screwdriver to tighten the ring clamp connectors if needed.

Inspect the fuel line to be sure there are no kinks or cracks – harsh weather can cause the hose to split, which can prevent a steady supply of fuel from reaching the motor. If it’s split near either end, cut off the damaged portion and reconnect the line with its hoe clamp. If the split lies toward the middle of the line, you can use a piece of heavy tape to patch it temporarily, but you’ll need to replace it as soon as possible.

Next, inspect the spark plugs for signs of corrosion. Use a small piece of fine sandpaper or a heavy-duty cloth to gently scrape the points clean, and make sure they’re properly seated when you replace them.

Finally, make sure your fuel line isn’t blocked. Some fuel hoses have a plastic lining, which can break down and come loose inside the hose. Disconnect the line at the motor and squeeze the bulb to force fuel down the line. Be sure to hold the line over a bucket to catch any gasoline that pours out. If the flow of fuel is sluggish, the line is probably blocked, and you’ll have to replace it.

If your motor has both an internal and an external tank, check the switch and be sure to set to the appropriate one. It’s easy to bump the switch while you’re moving around on the boat or repositioning the motor, and you might not even realize which tank is active. Additionally, make sure the tank vents are free from obstructions, and try squeezing the bulb a few times (be careful not to flood it!) to get gas from the tank up to the motor.

Second, take a look at the kill switch. If the engine doesn’t sound like it’s even trying to start, make sure the kill switch is properly attached by taking it out and reseating it firmly.

If your motor has an electric start, check the battery. It may be dead – in which case, you might need to use the pull cord to turn the motor over manually until the flywheel builds up enough momentum to let the motor start.           Additionally, inspect the cables for signs of corrosion, be sure they’re securely connected, and if your motor has a fuse, try replacing it.

Sometimes a motor seems like it’s about to start, but it can’t quite seem to get going. If your motor almost starts but then peters out, try starting it with the choke and without, and try a little more throttle, or a little less. Sometimes a little more or a little less gas is all a finicky power boat motor needs to start.

Alternately, if your motor starts but then dies as soon as you put it in gear, you probably have something tangled around the propeller. As it starts to spin, the obstruction creates resistance; enough resistance and the motor will stall out. Disconnect the battery leads so the motor can’t start unexpectedly (better safe than sorry!) Then tilt the motor into the boat to raise the propeller out of the water, and check for obstructions. Fishing line, weeds and other plants, and lost or discarded tie-up ropes are frequent culprits. Use a sharp knife to cut the prop free and completely untangle each of the blades.

Maybe You’re Trying Too Hard

If you’ve been trying to get your motor started for some time and you can smell gas in the air, it could be that you’ve flooded it. Take a break, and leave the motor alone for fifteen to twenty minutes – long enough for the excess gas to drain back down into the fuel tank. Then check the requisite factors (fuel shut-off valve set to “on,” starter connected, etc.) and try again.

Three Takeaways for Safe, Enjoyable Boating

Whether you enjoy fishing, water skiing, or just motoring around in the sun and feeling the breeze in your hair, a boat can be the centerpiece of your summer activities. To ensure everyone has a safe, frustration-free adventure every time you leave the shore or dock, keep the following important guidelines front-of-mind.

First, service your outboard motor regularly, and check each of the key components carefully to ensure reliable operation. Second, understand how your motor works, and know how to diagnose and resolve problems if it refuses to start or keep running. Third, take a boat safety class and make sure everyone on board abides by the rules.

Operating an outboard motor can sometimes prove challenging, but you shouldn’t let it put a damper on your boating fun. With a little knowledge and good troubleshooting skills, you and your family can enjoy making memories on your personal watercraft for years to come.