The reason why your jet ski won’t start and is beeping lies either in the computer or the engine. Jet skis are relatively straightforward machines that include a simple engine, a computer system, and a body. The body doesn’t affect the machine’s ability to start. The beep system built into your jet ski will help you diagnose and solve the problem.

Jet skis and Beep Codes

I’ve been there. Pull my ski out for the summer and head to our ramp to launch. Get my trailer in the water, and then give the start button a push before releasing my wench clip. You probably do the same when launching. But sometimes this happens:

Despite following the normal startup procedures, the engine doesn’t seem to want to start. Instead of 2 short beeps followed by the hum of a running engine, all you hear is a single beep. 

While you may not be exactly sure what that beep means, there is a connection between the beeping you hear and the fact that your jet ski isn’t working. 

If your jet ski won’t start, you should start with a few very basic steps first before calling a repair shop or trying to make significant repairs yourself. 

Consult the Owner’s Manual

If you purchased your machine second-hand and don’t have a manual, you may be able to read one online.

Search for the brand and model of your jet ski, and add the words “read-only manual.”

Not all manuals are available that way, but some are. You may have to set up an account before you can see the manual.

A second option is to purchase a new one from a dealer that sells them online. A third possibility is to buy a used one from Amazon, eBay, Craigslist, etc.  

Assuming that you have access to an owner’s manual, you should read through the start-up procedures to make sure you didn’t omit or add a step.  Every step is essential and must be completed in the correct sequence.

You’ll want to check your DESS (Digitally Encoded Security System) lanyard carefully.

We’ll get into the details of the DESS and lanyard more specifically a bit further, but first double-check the list below.

  • If you have more than one jet ski, is this lanyard the one made for this machine?
  • Is the lanyard right side up?
  • Is the lanyard warped or corroded?
  • Does it show any signs of wear at all?

Read through the pages explaining your jet ski’s beep codes. Make sure you’re not triggering error codes by waiting too long between steps.

If a step is not completed in the set time frame, an error beep will sound. You must start the entire sequence over again.

If you try to full sequence again and your machine’s display shows actual error codes, find the displayed code in your manual and proceed based on the information provided.  

If there is no code displayed, read the manual’s troubleshooting section before proceeding further.

If you’ve ever experience this, read on to know what to do

Identify the Type of Your Jet Ski Engine

Originally, all jet skis had 2-stroke engines. Two-stroke engines are light, powerful and easy to maintain.

Their high power-to-weight ratio means that they can provide quick acceleration, which is a huge advantage for a jet ski. 

Two disadvantages of these engines are that they are not fuel-efficient and they cause considerable amounts of water pollution (source).

Because of the amount of water pollution emitted by 2-stroke engines, all models of jet skis are now manufactured with 4-stroke engines.

These engines are larger, heavier, and more complicated because of the addition of valves, but they are more fuel-efficient. They also cause far less pollution (source).

If your jet ski is more than 10 years old, it probably has a 2-stroke engine.

Otherwise, it could have either type, so you’ll want to make sure you know which type you are working with. 

Knowing engine type is critical because: 

  • Two-stroke engines require oil to be added to the fuel – four-stroke engines don’t.
  • Four-stroke engines have valves – two-stroke engines don’t. 
  • Four-stroke engines are larger, heavier, and more complicated to service on your own.

Visually Inspect Your Jet Ski for Clues to Problems

Where you stored your jet ski and how well you covered it will greatly affect how well it fared during the off season.

  • Are there signs that bugs or small rodents nested in the exhaust system?
  • Have critters used the exhaust system as a freeway into your engine? 
  • Are there water drops in several locations on the jet ski, indicating excessive moisture?
  • Do the storage areas look damp or smell musty?
  • If you used our Battery Tender recommendations or other trickle charger, is it still attached correctly?
  • Are there stains under your jet ski that indicate fuel or lubricant leakage?

These signs indicate the likely culprits and are good starting points for troubleshooting.

Verify That Your Engine Has Fuel and Power 

There are a couple of basic steps that you should be able to perform in order to verify that your engine has both fuel and power before you make an appointment at the repair shop. 

Check for fuel in the tank

This is seemingly obvious, but sometimes overlooked. The first step is to make sure your tank has fuel.

If it doesn’t, you may have found the culprit. However, if your machine has been sitting over the winter months, you may want to do more than verify that the tank is not empty before hitting the water. 

Check to ensure that the fuel is clean and uncontaminated

If you did not top off the gas tank, there’s a strong possibility that moisture condensed inside your tank and that the water drops seeped into your gas.

If you have a 2-stroke engine, you’ll need to add the prescribed amount of 2-stroke engine oil to the gas tank. The oil lubricates the engine parts so that they don’t overheat.

Listen for engine cranking when starting your jet ski

  • If your engine won’t crank, the battery is dead and must be charged. 
  • If nothing happens after you charge the battery, make sure the cables are clean.

Now that you know your jet ski has fuel and battery power, you’re ready to try starting it again. 

If you need help with any of the above, it may be worth buying a full shop manual for your specific ski.

Keys to Understanding What the Beeping Means

Jet skis use a beeping system to help owners know when their machine is ready to operate, when routine maintenance is required, or when there’s a serious issue.

Sea-Doo’s system is the most elaborate.  To learn more about specific beep codes for the Sea-Doo, take a look at the article titled Sea-Doo Beep Codes.

The specific beep codes for a Sea-Doo, Yamaha or Kawasaki jet ski differ.

Your owner’s manual is the hub for understanding exactly what your machine’s beep codes mean.

Before you can understand the manual, though, you must understand a few key terms. 

PWC (Personal WaterCraft)

This is the official name of the vehicles commonly known as jet skis. PWC would apply to skis made by Sea-Doo, Yamaha, Kawasaki, and any other company.

Like “Kleenex” has come to apply to all brands of facial tissues, Jet Ski–which was the name of Kawasaki’s first stand-up water scooter–is also a generic name for PWCs (source).

MPEM (Multi-Purpose Electronics Module) 

This is the master part that controls the electronics on a jet ski.

The MPEM controls the CDI (an acronym for capacitor discharge ignition, the “brains” of a jet ski’s ignition system), the on/off button, the DESS–which is explained below–and a few other items. 

DESS (Digitally Encoded Security System)  

If your PWC is a Sea-Doo, then it has a DESS. The DESS is an electronically-guided safety and anti-theft feature.

The visible part of the DESS is a lanyard with a numerically coded computer chip on one end.

When the lanyard is connected to the DESS post on the Sea Doo, the machine can be started. Without it, the machine won’t start.

This feature makes a jet ski harder to steal, because the code is unique to each Sea Doo.

Like key fobs, DESS lanyards aren’t interchangeable. No one could use his or her lanyard to start someone else’s machine. 

SeaDoo keys

The DESS is also a significant safety feature. When used as intended, the other end of the DESS lanyard is connected to the driver’s PFD (personal flotation device.)

If the driver falls off the jet ski, the lanyard separates from the post and the engine shuts down immediately. 

Additionally, a DESS prevents children from being able to turn on a jet ski simply by watching an adult and memorizing the ignition steps. Without the lanyard, the machine won’t start.

On many machines with a DESS, 2 short beeps signal that the jet ski is ready to start. Those beeps are music to a Sea Doo owner’s ears. 

What Potential Fixes Does the Beep Code Signal? 

A jet ski integrates a computer system with a 2-stroke or 4-stroke engine. Some beep codes indicate computer problems.

Some indicate engine problems. Some codes remind you of routine maintenance that should be done soon. 

Sea-doos have 2 layers of beep codes–general mode and diagnostic mode.

To switch from general mode to diagnostic mode, you simply press the start/stop key a specified number of times.  

Your jet ski’s owner’s manual will contain the exact beep code for your machine. It’s the best reference to help you accurately diagnose the problem.  

General Beep Codes 

Several beep codes indicate issues with the DESS lanyard. The jet ski beeps if you use the wrong lanyard, if the correct lanyard is inserted upside down, or if the lanyard is warped or otherwise unreadable.

Other codes signal problems with the MPEM. One long beep often means that the MPEM isn’t receiving the message it needs to “open up” the computer system. A series of 8 short beeps means that the MPEM is defective. 

Self-Diagnostic Beep Codes

Beep codes in the self-diagnostic mode indicate different DESS or MPEM issues.

Two short beeps in the diagnostic mode indicate corrosion or a bad magnet on your lanyard.

Two long beeps mean there’s a disconnect between your lanyard and your DESS. Three beeps signal a short circuit in one of the systems. 

Understanding Codes When You’re on the Water

Some codes occur while the machine is running and indicate a serious issue that needs immediate attention.

An indicator light accompanied by a beep signal that your jet ski’s battery needs to be charged soon. A continuous beep means that the engine is overheating. 

Preventing Problems When Storing Your Jet Ski

Your goal now is to determine the cause of the problem and get your jet ski running. It’s hard to concentrate on what you might have done to avoid these difficulties.

But what should you determine now to do at the end of the season in order not to repeat this scene? How should you properly winterize your jet ski? 

Drain the Water from the Engine’s Cooling System

The water in the cooling system of your jet ski needs to be there when you’re riding. It keeps your engine from overheating. But if it’s left to sit in your machine, it will cause lots of problems. 

To drain the water without damaging your engine, tilt your jet ski up a bit in the front.

Run your engine for approximately 30 seconds, while you occasionally turn the handlebars to the left and right.

Turn your jet ski off for 30 seconds, then repeat the process until all the water drains. 

Protect the Fuel Supply

Refill the fuel tank and add a fuel stabilizer so that the fuel doesn’t get gummy while your Sea-Doo is stored.

Moisture can condense inside a partially-full tank during cool weather and foul the fuel.

Fuel that’s not stabilized tends to clog the carburetor when the engine is started the next time.

Remove the Spark Plugs

Visually inspect them for signs of electrode wear or black tips, which signal that the plugs may need to be replaced before you ride again in the spring,

Wipe each spark down with a clean rag and replace them once you lubricate the engine.

Lubricate the Engine

Using a product designed for jet skis, spray the carburetor and spark plug cylinders.

Place a clean cloth over the cylinders and press the start button. The engine won’t start, but the action will disseminate the lubricant.

Check and Charge Battery

Carefully read and follow any safety instructions printed on your battery, then disconnect the battery terminals, negative terminal first.

Remove any residue from the terminals. Attach a trickle charger to your battery, following the manufacturer’s instructions. 

A relatively warm place is better than a cold location but avoid the urge to tuck the battery away in the corner or closet of a room in your home. Batteries can radiate dangerous fumes. 

Clean and Protect the Exterior

Your jet ski’s exterior has been battered by sun, wind, and water all season. Before you put your machine away for the winter, carefully detail and clean its exterior. 

This will prevent some issues and provide added protection during months of storage.  

Remove all your gear

Check all storage places carefully. Damp gear left closed-up for several months becomes a breeding-ground for bacteria, which you want to avoid.

Wash the exterior with mild soap suitable for your jet ski

Remove all grime, algae and any other debris from the hull and entire shell. If you ride in salt water, be especially careful to remove all salt particles.

Wash down the seat cushions and handles, too. Finish the wash by cleaning the bilge area.

Thoroughly dry your machine

In this case, moisture is the enemy. Dry the entire jet ski. Check the hull for water.

Dry storage compartments if water has seeped into them. Leaving water in hidden compartments over months of storage is sure to cause problems for you next year. 

Paint the bottom of the ski if it shows wear

If the bottom of your jet ski is showing wear and tear, you may want to consider painting it before putting it in storage. Doing so will protect it from further damage.

Details for how and when to paint the bottom of your jet ski can be found in “Painting the Bottom of a Jet Ski.”

Wax your jet ski

Using a specialty PWC wax or car wax will protect the surface and create an attractive sheen. Waxing your jet ski pre-storage is the best way to go about protecting the surface.  

Allow for Ventilation When Storing Your Jet Ski

Closed areas like storage units and areas under the hood and other covers will attract and trap moisture, which can lead to musty odors and possibly allow mildew to grow.

Use an empty plastic water bottle to prop open the lids of shallow storage areas and covers.

Set a small box of charcoal inside the larger storage units. The charcoal will absorb any moisture.

Cover the Exhaust System With a Wool Cloth

Covering the exhaust system with a wool rag will keep moisture from building up – the wool will absorb moisture.

The cloth will also keep insects or small critters from gaining access to the engine.

Cover the Jet Ski with a Durable Cover for Protection

Covers aren’t absolutely necessary in every situation, but they are always a good idea. I wrote a post on cleaning your ski cover regularly. There are links to aftermarket covers in that post if you’d like to save money on one.

If you live in a moderate climate and store your jet ski in your garage, you can safely use a lightweight, inexpensive cover, as long as it is large enough to enclose the whole machine. 

If your garage temperature dips below freezing during the winter months, you may want a thicker canvas cover that provides more protection.

If you store your jet ski outside, you will need a cover sturdy enough to hold up against winter wind and rain (or snow).

It must fit snugly enough to prevent insects and small animals from slipping inside.  

NOTE: If you store your jet ski in a spot that gets cold, you’ll also need to winterize the exhaust system.

Check your owner’s manual for instructions about how to do this, and to see any other recommendations the manufacturer makes regarding your particular machine. 

Final Thoughts

To run well, jet skis need proper maintenance. When something is amiss with your machine, its system of beep codes helps you diagnose the problem.

Understanding the beep codes will help you operate your jet ski safely and alert you when you need to perform routine maintenance. 

Following each of the above steps will protect your investment and help ensure that you will be able to quickly get on the water next season.