We’ve all been there. Eager to jump in the dinghy and land on shore after laying anchor on the mothership. Just one problem, the dinghy outboard wort start. When they work, outboards are great, but unfortunately they are notorious for failing at the most inopportune moment. Adding to the challenge is that many times the outboard belongs to a charter company, so you may not understand exactly how it works or how well it has been maintained.
The good news is that most failures have fairly simple causes that can be corrected fairly quickly. Other problems require some tools or spare equipment, but can also be corrected fairly easily with a little knowhow. More serious problems may require a professional or a weekend in the garage for the more resourceful DIYers.
As with most gear, it’s good to google some manuals online. Most outboard manuals do a good job of laying out the engine, describing how it works, and even offering some sort of troubleshooting checklist.
But if you peruse a few of these checklists, you’ll see that there is a lot of overlap and duplication. That’s because a lot of these problems have common causes. If you understand the basics of how an engine works, you’ll be able to troubleshoot a lot of different issues.
The basic concept of a gas engine is that an explosion happens in the engine cylinder to drive the piston and turn the output shaft which drives the propeller. In order for the explosion to happen, an appropriate mixture of fuel and air needs to be in the combustion chamber and the spark plug needs to ignite it.
Fuel System Checks
Most problems are in the fuel system. If a steady, clean, sufficient supply of fuel is not reaching the combustion chamber, the engine with fail to start, sputter, or die.
If the fuel is not freshly purchased, check that it isn’t spoiled. Gasoline can go bad in as little as two months. Globules and grit forming in the gas indicate that it is spoiling. Other gunk may indicate that it has been contaminated or there is a problem with the fuel filter. If you can’t see well enough into the tank, pour or scoop some gas into a small clear cup.
Check that there is sufficient fuel in the tank, either in the engine head [1] or auxiliary tank. A small dinghy outboard doesn’t consume much fuel, but if the tank is dry or close to it, you’ve found your problem.
Check that any fuel tank air vents are open [6]. Closed vents will create a vacuum in the fuel tank and resist the engine drawing fuel.
Some engines have a fuel shut off switch, usually found on the side of the engine head [2], to shut off the fuel system during storage/transport. Make sure that it’s set to open when starting the engine.
Be sure the throttle [9] is set just above idle, or slightly higher if there is trouble starting.
If nothing else works, take off the head cover [16], and find the fuel filter. Make sure it’s clear and clean, or replace it if necessary.
Air System Checks
The second most likely culprit is the air system. The choke knob [7] controls the amount of air in the fuel-air mix, and the fuel is mixed with air by the carburetor. When cold-starting the engine, the choke knob should be pulled all the way out to minimize air and create a fuel-rich mixture to aid ignition. If the engine is warm, or you suspect the engine is “flooded” – i.e. already has fuel in it, or has too much fuel – push in the choke knob to allow air to get in.
If adjusting the choke doesn’t work, the problem may be the carburetor. You’ll need to remove the head cover [16] to inspect the carburetor. Regular applicate of carb cleaner can prevent problems, but if the carburetor isn’t functioning properly, it’s best to have it serviced by a professional.
Ignition System Checks
If the engine is getting good fuel and the fuel-air mix is right, but it still won’t start, there could be a problem with the ignition system.
Make sure the engine is in neutral [3]. If the start cord [7] feels like it is locked, it may mean the engine is still in gear.
Check to make sure the engine kill switch [10] has the safety lanyard inserted correctly.
If nothing else works, you can check the spark plug. It will likely only be accessible after removing the head cover [16]. You may need a special long socket wrench to loosen the spark plug, but it’s not too difficult to check, clean, or replace. Check your manual for instruction specific to your motor.
Cooling & Lubrication System Checks
These problems occur less frequently, but if the engine starts, then suddenly shuts off, it may have locked up, due to inadequate lubrication or overheating.
To prevent overheating, make sure cooling water is streaming out of the back of the engine after it starts. Make sure the cooling water intake [12] isn’t blocked, and be sure to flush the cooling system with fresh water from a hose every so often.
Check the oil level, color and opacity via the viewing window [15] and change it when necessary. See your manual for oil change instructions.
