Troubleshooting A Flooded 2-Stroke Outboard: Step-By-Step Guide

Starting a flooded 2-stroke outboard boat engine can be a tricky task, but with the right approach, it is possible. One common suggestion is to fully open the throttle and crank the engine to admit as much air as possible, which helps clear the excess fuel. This method may need to be repeated several times, and in some cases, it may be necessary to leave the engine for a while to let the fuel evaporate before attempting to restart. It is also important to ensure that the choke is off when trying to start a flooded engine. Additionally, it is recommended to check the spark plugs and dry them if they are wet, as this can also aid in starting the engine.

Open the throttle all the way and crank the motor

Opening the throttle all the way and cranking the motor is a common method to start a flooded 2-stroke outboard boat engine. This technique is known as a "clear-flood start" and can be effective whether your engine has a carburetor or fuel injection.

Here's how it works:

When you open the throttle all the way, you're allowing as much air as possible to enter the engine. If your engine is equipped with a carburetor, fully opening the throttle will open the throttle plates inside the carburetor, providing free passage for air to enter. In the case of a fuel-injected engine, cranking the engine with the throttle wide open signals the engine's electronic control module to enter a clear-flood mode, where it withholds fuel but allows air to enter the engine.

This "excess air" then combines with and burns away the excess fuel that has flooded the engine. It's important to note that an outboard engine floods when there is too much fuel in the air-fuel mixture, causing it to become too rich to burn. By opening the throttle and cranking the motor, you're essentially introducing more air to balance out the excess fuel, allowing the engine to start.

It's worth mentioning that time is usually on your side when dealing with a flooded engine. If your initial attempt to start the engine doesn't work, you can wait for a few minutes and then try the clear-flood start again. This gives any excess fuel trapped in the carburetor or injectors time to evaporate, making it easier for the engine to start.

Additionally, it's important not to crank the outboard motor for more than 10 seconds at a time. You can crank it up to three times, but then you must allow the starter to rest for about two minutes before attempting to crank the engine again. This precaution helps prevent heat damage to the starter and mechanical components such as the Bendix drive.

While opening the throttle and cranking the motor can be an effective way to start a flooded 2-stroke outboard boat engine, it's always a good idea to consult a certified marine technician or refer to your engine's manual for specific instructions pertaining to your particular model.

Dry the spark plugs

Drying the spark plugs of a flooded 2-stroke outboard boat engine is a crucial step in the process of resolving the issue. Here is a detailed guide on how to effectively dry the spark plugs:

Locate the spark plugs: Before you begin the drying process, you need to locate the spark plugs in your outboard engine. They are usually situated near the engine's cylinder head.

Remove the spark plugs: Using the appropriate socket or wrench, carefully remove the spark plugs from the engine. Be gentle to avoid damaging the threads or any other components.

Inspect the spark plugs: Once the spark plugs are removed, visually inspect them for any signs of damage or excessive carbon buildup. If the spark plugs appear to be in good condition, proceed to the next step.

Reinstall the spark plugs: Once the spark plugs are completely dry, carefully screw them back into the engine, ensuring they are tightened securely but not overtightened. Refer to your engine's manual for the correct torque specifications if needed.

After completing these steps, your spark plugs should be effectively dried, and you can proceed with the rest of the steps to start your flooded 2-stroke outboard boat engine. Remember to exercise caution throughout the process and consult a professional mechanic if you have any doubts or concerns.

Check the carb needle and float assembly

To check the carb needle and float assembly, you must first remove the carb float bowl. This will allow you to inspect the condition of the float and needle. If you are unable to remove the bowl, try tapping it with the handle of your screwdriver to dislodge it.

Once the bowl is removed, you will see the float. It is attached to the carb body with a long, thin pin. Tap the pin out gently with a small hammer and screwdriver. If your screwdriver is too large, use pliers to grip the pin and pull it out.

The float needle should be in the notch on the float. If it is not, check the needle seat. The seat is located under the float in the carb housing. The float needle may be stuck in the seat, so use small pliers to pull it out.

Now, check if the needle slides in and out of the seat freely. If it does not, this is likely the source of your fuel problem.

If your needle is stuck, you can try using a small amount of lubricant to loosen it. You may also need to clean or replace the needle and seat.

Disconnect the fuel line and crank the engine

Disconnecting the fuel line and cranking the engine is a common practice to prevent fuel from flooding the engine and causing damage. Here are some detailed steps and tips to guide you through the process:

Step 1: Locate the Fuel Line

The fuel line is usually connected to the engine near the carburettor. It is typically a flexible hose that carries fuel from the tank to the engine. Make sure you have a basic understanding of your engine's components before proceeding.

Step 2: Prepare the Engine

Before disconnecting the fuel line, it is recommended to run the engine for a few minutes to warm it up. This will help reduce the risk of any fuel residue accumulating and causing issues. Ensure the engine is running smoothly before proceeding to the next step.

Step 3: Disconnect the Fuel Line

Gently pull or unscrew the fuel line from the engine, depending on the type of connection it has. Be cautious and try to minimise any spillage during this step. Have a rag or absorbent material ready to wipe off any spilled fuel. It is also advisable to wear gloves and eye protection for safety.

Step 4: Crank the Engine

Once the fuel line is disconnected, crank the engine by turning the key or pull-starting it, depending on your outboard motor's design. Keep cranking the engine until it stops, as this will help clear out any remaining fuel from the lines and carburettor. This process is often referred to as "running the engine dry."

Step 5: Reattach the Fuel Line

After the engine has stopped, reattach the fuel line securely. Ensure that the connection is tight and there are no leaks. This step is crucial to prevent fuel leaks and potential safety hazards when you use the boat next time.

Tips and Best Practices:

• It is generally recommended to disconnect the fuel line and run the engine dry only when you plan to store the boat for an extended period. Frequent disconnection of the fuel line may not be necessary if you use your boat regularly.
• Consider using a fuel stabiliser to prevent the fuel from deteriorating, especially if you won't be using the boat for a while.
• Some people prefer to drain the carburettor bowl to ensure no fuel is left in the engine. This can be done by removing the drain plug on the carburettor.
• Always exercise caution when working with fuel. Ensure proper ventilation and avoid any open flames or sparks during the process.
• If you're unsure about any steps or have a complex engine setup, consult a marine mechanic or a professional with experience in outboard motors.

Check the choke

The choke is an important component of an outboard boat engine, and it is crucial to check it, especially when starting a flooded 2-stroke engine. Here are some detailed instructions and considerations regarding the choke:

First, it is important to understand what the choke does. When you engage the choke, you are essentially restricting the air supply to the engine, which results in a richer fuel-air mixture. This richer mixture is easier to ignite and helps the cold engine start. On older carbureted engines, the choke is usually engaged by pulling out a knob or lever. Newer engines may have an electric choke that is activated by pushing or turning a key.

When starting a flooded 2-stroke outboard engine, it is essential to ensure that the choke is off while the engine is drying out. Keep the choke disengaged to allow the excess fuel to evaporate and the spark plugs to dry. Attempting to start the engine with the choke on can lead to further flooding.

Once the engine has had sufficient time to dry, typically around 10-30 minutes, you can prepare for the starting procedure. At this point, you should ensure that the choke is functioning correctly. Check that the choke knob or lever moves smoothly and is not stuck or jammed. A stuck choke can cause issues with starting and engine performance.

After confirming the choke's functionality, you can proceed with the starting procedure. The specific steps may vary depending on your engine model, but here is a general guide:

• Engage the choke by pulling out the knob or lever, or by activating the electric choke.
• Prime the fuel bulb until it is firm or hard. Some engines may have a primer bulb that you need to pump to ensure sufficient fuel pressure.
• If your engine has a manual choke, turn the key to the "on" position while holding the choke. You may need to wait for a beep or system check lights to turn off.
• With the choke still engaged, attempt to start the engine. Crank the engine for a few seconds, then release the choke and try starting again.
• If the engine struggles to start, you can try bumping or pushing the choke in briefly during cranking to provide additional fuel. Alternatively, you can try starting with the choke partially engaged.
• Once the engine starts, slowly release the choke to the "on" position. You may need to adjust the throttle slightly to keep the engine running smoothly.
• Let the engine warm up for a couple of minutes before proceeding.

It is important to note that the starting procedure may vary depending on the make and model of your outboard engine. Always refer to your owner's manual for specific instructions. Additionally, older engines may have unique starting procedures that you will need to learn and replicate consistently.

Frequently asked questions