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Can You Use Starter Fluid On An Outboard Motor?

to use starter fluid on an outboard motor

You’re ready for a day out on the water, but your outboard motor won’t start. The quickest and most obvious solution is to reach for a can of starter fluid.

But are you supposed to use starting fluid on a boat engine?

Is it okay for both 2- and 4-stroke motors? 

When and how should you use it? And are there times when you absolutely shouldn’t use it?

Keep reading as we dive into the answers to these questions and more!

What is Starter Fluid?

Start Your Engines! Fuel System Revitalizer and Starter Fluid

Starter fluid is a substance used for starting motors that won’t start on their own. It is particularly useful for engines that have been sitting for a long period of time, or for those that you are having trouble with starting during cold weather. 

Starter fluid is usually made of ether or a combination of other highly flammable chemicals. It is much more easily combustible than fuel, especially in cold weather. 

This is why it is so effective; it requires far less output from the starting components to actually get the engine to start. 

Starting fluid definitely has its place and is useful for a variety of motors. You have to know how to use it properly though, otherwise, you could damage your motor. And it is not appropriate in every situation. 

Starter fluid was first made for use in professional settings and was specifically meant to be used on diesel engines without preheat settings. 

Any other uses cannot be completely recommended. Starter fluid does have many applications, but you have to be careful when using it.

Can You Use Starter Fluid on an Outboard Motor?

use starter fluid on a boat engine

This brings us to the main question of this article. Outboard motors generally aren’t diesel-powered, so is it okay to use starter fluid on your boat engine?

The short answer is yes. 

Starter fluid can be used on nearly any motor, provided you are following the instructions and using it sparingly. 

That being said, you should be aware of the dangers of starting fluid, which we’ll talk more about in the following sections. 

Whatever you’re using starter fluid for, it should not be used repeatedly; if you’re having to spray starter fluid on your motor every time you go to use it, there’s an underlying problem that will need to be fixed. 

Using starter fluid over and over again may actually worsen the problem. 

So, only use starter fluid as needed, and if your motor won’t start the next time you try, your best bet is to check for the root cause of the problem.

Honda 9.9 wont start. Runs on starting fluid.

There are two types of outboard motors; 2-stroke and 4-stroke. Depending on which one you have, you may need to use starter fluid differently or with more care. 

Let’s take a closer look at each one and how to safely use starter fluid to get it running.

2-Stroke Motors

2-stroke outboard motor

You have to be extra careful when using starter fluid with 2-stroke motors; in fact, people are often cautioned against using it if their engine is a 2-stroke.

While it is okay to use starter fluid if you have a 2-stroke outboard motor, you will need to use it very sparingly and only according to the directions on the package. 

The biggest problem when using starting fluid on your 2-stroke is user error–in particular, using too much fluid or using it over and over again.

In 2-stroke engines, oil is mixed with the fuel in the cylinders; this oil lubricates the metal parts of the engine as they rub against each other.

The problem is, starting fluid is an excellent and highly effective emulsifier. So, using too much starter fluid can easily wash away the oil lubricating the cylinders, causing the parts to scrape against each other–like joints without cartilage. 

This repeated scraping action will cause significant wear and tear, and eventually, you may have to replace the worn down components of the engine. 

If you need to use starting fluid on your 2-stroke motor, chances are you already have an underlying problem that needs fixing. 

If the engine repeatedly won’t start even if you’re using it regularly, don’t ignore the problem by using more starter fluid–take the motor to the repair shop and try to find out what the root problem is. 

Starter fluid may seem like a quick fix, but using too much of it, or using it over and over again, may cause more damage to your outboard motor in the long run.

4-Stroke Motors

4 stroke outboard motor

Starter fluid is more commonly recommended for use with 4-stroke motors, as they are designed differently from 2-strokes and aren’t as prone to issues from using too much starter fluid.

Again, you should always endeavor to use it in small doses. It doesn’t take a lot of starter fluid to get your engine running, and using too much will eventually cause major problems with the engine.

This may even ruin your engine over time, or lead to costly repairs.

Starter fluid won’t cause as much wear on 4-stroke motors, and any damage that does occur will likely happen slowly. In fact, occasional use of starting fluid may even prevent certain types of wear to starters and other components. 

Still, you should never use starting fluid on a regular basis. As with 2-stroke motors, if your 4-stroke engine needs starter fluid every time you try to start it, there’s most likely a problem with the engine.

Starter fluid is most often used on engines with carburetors as opposed to fuel-injected systems, though it can be used with both. Again, follow directions on the fluid can, and be careful not to use too much.

Three Best Uses for Starter Fluid

In the above sections, we talked about the problems frequently caused by overusing starter fluid. But, as mentioned, there are also times when it can come in handy.

So, you may be wondering: when is it okay to use starter fluid? How can you do so without hurting your engine? In general, what are the best uses for starter fluid? 

When Cold-Starting

If you’ve ever tried to start your car on a frigid morning in the middle of winter, you know that motors often struggle to start up in low temperatures. 

use starting fluid when cold-starting

This is because the starter uses fuel vapors to start the engine, and there are fewer vapors at lower temperatures.

Maybe you’re trying to start your outboard motor on a cold fall or early spring morning, or you’ve gone through a long period of cold weather and want to make sure your motor still runs. 

Whatever the reason, if it’s cold out, you may want to use a spritz of starter fluid to get the motor running. Use only a little bit, just enough to get the engine to turn over.

After Long Periods of Disuse

use starting fluid after long periods of disuse

Maybe it’s been a long time since you had a chance to hit the water. You head out to the garage and dust off your old outboard, which you have stored away months or even years ago. 

Chances are, you’re going to have some trouble getting it to start on its own.

In this case, there likely isn’t anything wrong with the motor; it’s just that, the longer it sits, the harder it will be to start because any fuel remaining in the tank will go stale and not produce the necessary fumes.

A quick spray of starter fluid should get you up and running again.

After Running Out of Fuel

If your motor dies from running out of fuel, you may have trouble getting it to start again even after filling the fuel tank. 

use starting fluid after running out of fuel

This is because the tank was allowed to go dry and the engine will need to run a bit to pump fuel through all the fuel lines again.

A bit of starter fluid should give the engine the umph it needs to start, and once it’s running, the new fuel will quickly become distributed throughout the tank and lines.


1/ Where Do You Spray Starter Fluid on an Outboard Motor?

This depends on the type of engine you have. You may need to spray it in the engine intake, near the air filter, directly onto the carburetor, or possibly onto a spark plug hole. 

If you’re not sure, refer to your motor’s manual and the directions on the can of starter fluid.

2/ Is Using Starter Fluid Bad for the Engine?

As we’ve already discussed, starter fluid can damage your motor if you use it every time you try to start the engine, or if you use too much of it at once. This is especially true with 2-stroke engines. 

Occasional use is okay as long as you follow the directions on the can. 

If you’re not sure how to use starter fluid properly, it might be a good idea to watch a demonstration by a professional first, or you could check out the following video:

How to Use Starter Fluid

Again, repeated uses or using too much can cause serious and permanent damage that will cost a lot to repair. 

If your engine seems to need starting fluid every time, take it to a repair shop to find out the root of the problem.


It’s okay to use starter fluid on an outboard motor as long as you do so with care. Make sure you know what you’re doing before you start, and only use a little bit. 

Don’t use it every time you need to start the motor and get the motor checked by a professional if it won’t start without fluid.