How to start an outboard motor that has been sitting

Dewinterizing your boat is the final step to getting back on the water in the spring. If you read our 10 Steps to Dewinterization Guide then you’ll have all the details for getting any boat dewinterized and ready to go. This article offers 10 easy to follow steps along with pro tips to get an outboard motor started up safely in spring.

Dewinterizing, or summerizing, an outboard motor involves attaching a garden hose, priming the fuel line, and starting up the motor after completing a thorough inspection for damages which may have occurred during freezing temperatures or were overlooked during winterization.

Before You Start Your Outboard Motor in Season

Every dewinterization process starts with the same basic idea: inspection. Cracks can develop in the motor and motor components when water is left in the system during the freezing temperatures of winter. Even Arizona gets below freezing during the winter.  If you find any damage, don’t move on to the next steps. Stop and decide what needs to be done to repair the damage. 

Pro Tip: Before you start any outboard after it has been in storage, first pull the plugs, spray WD-40 in the heads, leave the plugs out and manually turn the motor by the flywheel or prop. If everything turns smoothly, then you can go ahead and move on to the next steps.

Change the Oil and Oil Filter

If there is no obvious damage to the motor and the oil and oil filter weren’t changed in the fall,  go ahead and change them now. If you did, then fresh oil and a new oil filter from the fall should still be okay in spring. 

Pro Tip: Clean oil is gold or amber and dirty oil is black. Only run your boat with clean oil. 

10 Steps to Dewinterizing an Outboard Motor

Step 1: Attach a Garden Hose to the Motor

Use a garden hose with good pressure and secure a water muff on the end of the hose. It needs to be tightened just right. If you do it too tight, it will be really hard to disconnect, but not tight enough and it will leak and interfere with the water pressure.

Step 2: Clear Water Lint Screens of Debris 

The water lint screens are where the impeller sucks in water to cool the motor while it’s running. If any debris is left on the screens, there will be a problem with getting enough water through the screen to cool the motor.  

Step 3: Attach Water Muffs

It’s important to position water muffs over the lint screens so they’re covering the entire screen. This will give the impeller enough water to pull into the motor.

Step 4: Inspect the Propeller and Empty the Strainer

Inspect the propeller to make sure it is fastened tightly and rotating. If it’s loose and the motor is started, it can cause the propeller to come off and hurt someone. Next, empty the strainer then check all rubber parts and the impeller for damage.

Step 5: Prime the Fuel Line

It’s necessary to get the air out of the fuel system before starting the motor. Depending on what type of outboard the boat has, there are 2 ways to do this: 

If the motor is equipped with a primer bulb, make sure the fuel line is connected to the motor then give it a few squeezes until it feels firm. This indicates that the line is charged and ready to be started safely. 

If the motor does not have a primer bulb, just turn the key to the ‘run’ position and wait. It will beep then the fuel pump will start running. After a few seconds, the pump will clear the air out of the fuel line automatically, and it can safely be started. 

Step 6: Turn on the Water

Once the lint screens are cleared, the water muffs are attached, the fuel line is primed, and the garden hose is securely attached, it’s time to get the water going by turning on the faucet.  

Pro Tip: Never run your motor dry because it will destroy the rubber impeller. When starting a boat on land, make sure there is water in the drive

Step 7: Start the Motor

Put the shift cable in the neutral position, push into ‘choke’ and start the motor. 

Pro Tip: Have a friend to start the motor so more attention can be paid to the water line, which is crucial to the next step 

Step 8: Immediately Check for the Water Line 

Once the water has had a moment to be pulled into the motor, there should be a water line coming out of the motor. If there isn’t a water line, TURN OFF THE ENGINE IMMEDIATELY. 

Absence of a water line, which is a stream of water coming out of the motor, means that the impeller is not pulling water into the motor properly. Assuming everything was done properly in the previous steps, then this could indicate there is damage inside the motor. Stop and ask an expert for help. 

If there is a water line, then continue to run the motor for 5-10 minutes until the smoke dissipates and water is running clear

Pro Tip: If fogging oil was used to winterize the motor, then it is normal to see a lot of smoke when starting the motor for the first time in spring

Step 9: Move Through the Gears then Cut the Engine

After 5-10 minutes and the water is running clear, shift to ‘forward’ then ‘reverse’ to verify all positions are working. 

Pro Tip: Be sure the hose is out of the way of the prop!

Cut the motor and turn off the water. 

Step 10: Check Spark Plugs, Kill Switch, and Bilge Pump

If the spark plugs weren’t changed in the fall, then let the motor cool for a few hours and change them. If they were changed before putting the boat into storage, then they should still be okay. 

Check the kill switch. Hit the kill switch and pull the lanyard in to make sure it actually cuts the motor. This important safety step should not be overlooked.

Check the bilge pump. Turn on the switch and make sure the bilge pump not only runs, but pumps water out of the boat. Put the plug in the boat and use the garden hose and put water in the boat, then turn on the bilge pump. This does take a little extra effort but if it isn’t working, it’s better to know now than when the boat is sinking on the lake.

Final Thoughts

Following these pro tips and 10 steps to starting an outboard motor in the spring will save money and time when done properly. 

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An unfortunate downside to owning a boat is that sometimes your motor will have to sit for long periods of time without being used. This can result in difficulty starting your outboard motor, but not to worry, there are steps you can take to start your motor just like new. 

Here are 9 steps you can take to start an outboard motor that’s been sitting:

1. Remove the airbox and lubricate all components.
2. Drain old fuel from the fuel tank.
3. Connect a second tank full of brand new fuel. 
4. Replace oil cylinders and spark plugs if no longer functional.
5. Check and replace gear lubricant if needed.
6. Check the oil levels and replace or add more. 
7. Connect To a Fully Charged Battery or use a battery charger. 
8. Start the engine and run it using a garden hose. 
9. Enjoy your fully functional outboard motor.

In this article, I will go over these steps in-depth for starting your outboard motor that has been sitting for an extended period of time, as well as some of the most frequently asked questions about starting your outboard motor. So let’s get started. 

1. Remove the Airbox and Lubricate All Components

The first step to getting your old boat motor running again is to remove the protective box covering your motor. This will allow you to see what you are working with. Most airboxes detach pretty easily using the clasps on the sides. 

Once you have removed the airbox, you should begin lubricating all of the components. Especially those that experience a lot of movement when running, such as the throttle plates and the springs on the control linkage arm. 

These components have been sitting for quite some time, and some of them will be pretty delicate. Without proper lubrication, you risk the chance of breaking them when your motor starts up. 

When it comes to selecting a good lubricant for your motor components, I recommend STA-BIL Fogging Oil on Amazon.com. It will lubricate your motor parts easily and is very cost-effective. 

Be sure to be thorough when lubricating the components of your motor, especially when dealing with the linkage arm. 

2. Drain Old Fuel From the Fuel Tank

The next step you should take is to drain all of the old gas from the fuel tank and replace it with new. 

You will want to do this because when old gas sits stagnant in a tank for an extended period of time, it can become less efficient. 

Also, if old gas sits in your fuel tank for too long, the ethanol can attract water which can build up inside of your tank. Not to mention if fuel has sat for a very long time, it can collect dirt and other build-ups that will be sucked straight into your motor and can cause significant damage to your engine. 

This is why it’s best to drain any fuel that has been sitting inside of your tank for more than 6 months. But, again, it is better to be safe than sorry. 

To drain the gas from your fuel tank, simply open the valve and use an old jar or container to begin draining the unwanted gas. This step can take a few minutes, but it’s crucial in order to get your outboard motor running properly.

Just be sure to dispose of the old fuel safely and correctly. 

3. Connect a Second Tank Full of Brand New Fuel

Now that you are draining the old fuel that has been sitting inside of your tank, it is best to connect your motor to a second tank full of clean fresh gasoline. 

You can do this by switching the fuel lines out and reattaching it to the new container of gas. This way, your motor is only running clean fuel, and you can eliminate the possibility of your boat sucking in bad fuel that is stuck in your old fuel lines. 

Remember to be careful when handling gasoline and not to spill any on yourself as it is highly flammable. 

4. Replace Oil Cylinders and Spark Plugs if No Longer Functional

You will need to replace the oil cylinders and spark plugs if they look old and rusted. Sometimes they will merely need a good cleaning but if you are worried that yours are too far gone it is best just to replace these parts. 

Replacing your boat’s oil cylinders and spark plugs shouldn’t cost too much and is much more cost-effective than a broken motor. However, it’s also important to remember to lubricate the new hardware after installation to ensure everything continues to work correctly. 

5. Check and Replace Gear Lubricant if Needed

It’s essential to check that all of your gears are well lubricated and that the lube is not gritty or has too much water built up on it. As a general rule, you should replace your gear lubricant once a year or every 100 hours of use. 

If you notice any of these signs, it’s a good idea to clear the dirty lube and replace it with new ones so that your boat motor can run as cleanly as possible. 

To change your outboard motors gear lubricant, you will need:

• A large flathead screwdriver.
• Drain pan.
• Some cardboard.
• Fresh gear lube.
• Lube pump. 

Now you can definitely have this done professionally, but it’s relatively simple to learn how to do it yourself. 

To change your own gear lube, you will want to:

1. Unscrew your bottom vent plug. 
2. Unscrew your top vent plugs.
3. Once vent plugs have been loosened, lower your motor over your drainage pan.
4. Remove plugs completely, starting with the bottom one. 
5. Check the magnetic part of plugs for metal shavings indicating gear wear.
6. Check that there is no water in your oil as it drains into the pan.
7. Allow your oil to drain completely, then tilt your motor back up slightly. 
8. Plug the gear pump into your quality bottle of oil. 
9. Fill your gear case from the bottom to the top. 
10. Insert the tip of the pump into the gear case and lower the motor back down.
11. Slowly pump in the oil so that you avoid creating air bubbles.
12. When oil begins to come out of the top, you should stop pumping. 
13. Replace the plugs starting with the top ones. 
14. Clean up, and you’re all done.

For a more in-depth guide to changing your gear lube, you should definitely check out the Shoreline Marines video on this subject.

https://www.youtube.com/watch?v=cDS56zVfOuA

6. Check the Oil Levels and Replace or Add More

Just like an old vehicle, before starting up your outboard motor that has been sitting for a while, it is essential to check your oil levels. If you notice that your oil is low or if it hasn’t been changed in a while, it’s probably a good idea to just change the oil rather than topping it off. 

You can do this process yourself fairly easily or have it done professionally if you’d rather not. 

7. Connect to a Fully Charged Battery or Use a Battery Charger

Next, you will want to connect a fully charged battery to your motor or take the time to charge up the old battery using a battery charger. Battery chargers can take a long time to charge your boat’s battery fully, so you will want to do this ahead of time. 

You can acquire a new battery or battery charger at most auto part stores or online. Another option is to take your battery in to charge it at your local mechanic’s shop. 

Also, it is important to note that battery chargers can be dangerous and should never be left unmonitored since they can lead to your battery overheating and starting a fire. 

8. Start the Engine and Run It Using a Garden Hose & Muffs

The next step is to finally start your boat’s motor and run it using a garden hose to keep it from overheating. 

You don’t need anything fancy; a simple garden hose hooked to an outdoor spigot will do the trick. The primary goal in using water is to keep your motor cool. 

You can use boat muffs to hook to your garden hose and slip the muff over the intake holes on your motor so that the water will flow through the motor as it would when your boat is in the water when you go to start it. 

You can acquire boat muffs for relatively cheap, and I personally recommend Seachoice Motor Flusher on Amazon.com. They are easy to use and will get the job done nicely. 

Once you have your outboard motor started, it’s a good idea to leave it running for a little while. This will help everything to get lubricated and to keep the battery charged. 

9. Enjoy Your Fully Functional Outboard Motor

To keep your boat’s motor in the best condition, it is recommended that you take it out regularly or at least start it every so often. When your motor is getting regular use, it will stay in better condition since it’s regularly moving, and the lubricants are better able to keep all of their components coated. 

Now that you know that your motor is fully operational, you are all set to take your boat out on the water for a voyage. 

What You Will Need To Get Your Outboard Motor Started

Now that you know how to start your outboard motor after it has been sitting, here is a consolidated list of supplies you might need prior to getting started. 

What you will need to start your outboard motor safely:

• A fresh battery or battery charger
• New spark plugs (if needed)
• New oil cylinders (if needed)
• Lubricant or fogging oil
• A glass jar or container to drain old fuel into 
• New Oil
• A container of new fuel
• Boat muffs
• Garden hose

You may only need one of these items, or you may need several depending on how difficult the motor is to start. 

Frequently Asked Questions 

Next, I will take you through some of the most commonly asked questions about starting your old outboard motor that has been sitting. 

How Long Can Gas Sit in a Boat Before It Goes Bad?

Gas can sit in a boat for about 6 months before it goes bad. Some types of fuels will last longer, especially if a stabilizer has been added to them. While fuel with ethanol in it goes bad more quickly since it attracts moisture that will cause water to build up in the tank. 

How Long Can a Boat Motor Sit Without Running?

How long your boat motor can sit without running will significantly vary based on the type of motor, fuel used, and how your boat is stored. As a result, boat motors can sit without running anywhere from months to years. 

Can You Start an Outboard Motor Dry?

You can start an outboard motor dry, though it is not recommended to do so for more than a few seconds. When you start your motor dry, you risk the engine overheating. This is because water is used to keep the boat engine cool as it runs. 

How Often Should You Flush an Outboard Motor?

You should flush your outboard motor as often as your boat’s manufacturer directs you to do so. It is also recommended that you flush your motor after each use in saltwater and regularly after freshwater use. 

Final Thoughts 

Whether you are in the process of purchasing an old boat that has sat for some time or are simply looking to get your old boat back on the water, it is essential to start your outboard motor carefully. 

So remember:

• Always drain the old fuel from the tank and replace it with new.
• Lubricate all components.
• Start with a fully charged battery.
• Replace broken cylinders or spark plugs.
• Never start without running water to your motor. 

The overall process to get your old motor started isn’t too complex, but you will have to follow each step for success carefully.