The small four-stroke outboard engine is very simple. Max McHugh of Marine Matters explains how to solve the most common problems, from carburetor gluing to thermostat damage. Direct connection with GJW

This is a guide to the basic troubleshooting steps for our small gasoline four-stroke outboard engines. If you encounter a problem, please check our guide to find a problem in the diesel fuel system or electrical system.

The main reason for outboard engines not working is the fuel system, usually because the fuel remains in the engine in winter. The fuel produces ethanol through a chemical reaction, which prevents the engine from running. There may also be dirt clogging the filter, pipeline or carburetor. When cleaning, remove the flywheel cover and engine cover, and then remove the fuel tank.

Take out the fuel tank and remove the fuel pipe, and drain the fuel tank into the barrel. Flush the fuel tank with clean fuel. Before reconnecting the fuel tank, check that the filter is clean and flush with clean fuel as needed.

Four-stroke outboard fuel tank

Next, check the outboard carburetor. Close the fuel faucet, then open the drain screw on the side of the carburetor, and pour the oil into the barrel. Close the drain screw, open the fuel tap, and add clean fuel. If the engine is still not running, you may need to use a can of carbohydrate cleaner or clean carbohydrates in a workshop with ultrasonic cleaning.

Four-stroke external carburetor drain screw

Next, check whether the spark plug has sparks. You can use a spark plug tester to connect between the spark plug and the ignition (high voltage) wire. If you don't have a tester, unplug the plug, connect it to the wire, and then touch it to the engine body before pulling the power cord. You should be able to spot sparks. If not, you may need to install a new spark plug for the outboard motor.

Four-stroke outboard spark plug tester

Promotional features related to GJW Direct. If your engine won’t start, know how to find...

Promotional features related to GJW Direct. Rubicon says that keeping the anodes in good condition can prevent serious damage on the ship...

How to deal with gel coat fragments and get a perfect color matching surface. Bruce Jacobs learned from Mark Bakter...

If the safety rope is installed correctly, it is worth checking the stop button. It has a spring inside, but over time, the spring will degenerate, especially when the kill line is connected. If the button assembly is not pulled back, you may need to replace the button assembly.

Four-stroke outboard stop rope

If your outboard engine has seawater cooling (some are air-cooled) and you have not flushed the engine for a while, salt may accumulate in the engine. Run the engine in a bucket of fresh water, or use a hose and a set of flushing earmuffs, and check whether the water signal is unblocked before setting off. The small engine does not have an overheating alarm, but it will shut down as a fault protection. If you need to check the thermostat, take it out and put it in boiling hot water. You should see the spring moving. If not, you will need a new one.

The four-stroke outboard engine has an oil tank for lubrication. It should say how much oil you need. Fill and check the sight glass slowly, but if you add too much, use the drain screw under the sight glass to drain it into the bucket.

Four-stroke outboard oil sight glass

At the end of the season, don't forget to include the outboard in your winter maintenance. Make sure to empty or dry the fuel in the carburetor, and it's also worth emptying the tank and cleaning it. Leave the spark plug inside to prevent moisture from entering. If you store it on its side, make sure it is on the correct side.

Joint with GJW Direct

GJW Direct provides some of the most comprehensive and competitive marine insurance policies on the market. With more than 175 years of marine insurance experience, when you insure your yacht through us, you are dealing with ship insurance experts, allowing you to freely enjoy your time on the water. For more information, please visit: www.gjwdirect.com

The subscription fee for Yacht Monthly Magazine is about 40% lower than the cover price.

Print and digital editions are available through Magazines Direct-you can also find the latest offers.

YM contains a lot of information to help you make the most of your time on the water.

Follow us on Facebook, Twitter and Instagram.

In the December 2021 Yacht Monthly, you will...