Dead batteries, loose connectors, starter malfunction, security system still locked, wrong key, debris in impeller are some reasons why a jet ski won’t start. While these are more common, it may also be a starter motor issue or your PWC may have sucked something up from the water on its last ride. Low fuel is another consideration.

The one thing that could ruin your planned day of jet ski riding is finding out your jet ski won’t start.

There are a few different ways to find out what the exact issue is, so keep reading and you’ll be back on the water in no time.

Reasons Why Your Jet Ski won’t Start

It’s one of the most anticlimactic feelings in the world. You woke up bright and early. You got dressed. You slathered on the sunscreen, and you’re ready to hit the water.

You sit on your Waverunner, put the key in the ignition, and turn…and nothing happens. 

Because there could be several reasons why your ski won’t start, let’s begin by looking at the most obvious. 

Flat Battery

There is a good chance that the battery of your ski may have gone dead, or it may not have enough of a charge to begin with. 

How to Tell

When you turn your key or push the start button and there is no sign of life in your Waverunner or Sea-Doo (like the display coming on or a beep), there is a good chance the battery has died and may need to be replaced.

This state should remain no matter how many times you switch the ignition on and off.

However, if you find that the display works but it only makes a clicking or beeping sound, then your battery is too low to start the PWC.

Some users have reported that continuously turning the key and switching the ski on and off has resulted in a successful ignition (source).

If that is the case, there may be a loose wire or the battery cable may not be fully tightened. There may also be a dead cell in the battery, especially if it’s older, and it is recommended that a professional look at that issue. Most auto parts stores will run a free battery test for you.

Even if you feel like you have a trick to make your jet ski start, with a few taps here and a shake there, that is always a sign that, mechanically, there is something wrong under the hood.

For more information about beeping sounds, check out the article “Sea-Doo won’t Start, Just Beeps”.

Some Sea-Doos have battery in front compartment
Sea-Doo front mounted battery behind removable panels (not shown)

How to Fix It at the dock or site

Since all PWC’s are unique, it’s best to read the manual before opening it up. However, there are a few generalized features that will allow you to safely check and tighten your battery cables. First, you need to know where your battery is located. Some are easier to access than others.

The battery and system running through these crafts are able to release a high electrical output. Unless you have some experience working with electronics, it is best to allow a professional to have a look at your PWC.

The battery cable connections generally need to be very tight. Slide the caps off of each terminal. Use a large enough screwdriver to get them as snug as possible.

Keep a light coat of battery grease on the cable ends to prevent corrosion on the underside. Once you’ve done this, try and start the ski again. If you are unsuccessful, you can use a low power output battery booster to start it.

We keep this NOCO Boost Plus from Amazon on one of our skis at all times. It’s small, comes with a water resistant case which fits in the storage area, and will come in very handy if you are miles away from your launch ramp, dock or home when the battery decides to die.

After jump starting and riding for awhile, shut the engine off, wait a few seconds and then try a restart. If the battery is not holding a charge, it likely will need to be replaced.

Replacing the battery

In a case where the battery needs to be changed, the first thing to do is remove the black negative battery cable.

In general, this should be the first cable removed and the last one reconnected, whether you are working with the battery or not. Continue by removing the red cable as well.

Follow this by disconnecting the vent line. The screws in the battery holder should be removed fully. There should be a convenient battery holder located at the top of the battery that you can use to pull it out.

At this point, be very careful to pull out the battery completely vertically, as it often contains corrosive electrolyte liquid that can be very harmful if it makes contact with bare skin.

Better yet, wear protective gloves during the process as well. Once you have placed the battery on a flat, stable surface, unlock the tabs at the upper and lower part of the battery holder to free the battery.

Now the battery can be changed safely.  When returning it back into the Sea-Doo, maintain the same vertical hold and attach the black negative cable last (source). In the following video, I remove the rear battery from my Sea-Doo RXT 260.

Starter Relay

A starter relay, or starter solenoid, is responsible for transferring electricity from the battery to the starter and, in some cases, it might be the reason that your Sea-Doo won’t turn on (source).

How to Tell

Some users have said that they have to press the start button multiple times before their Sea-Doo turns on, and that’s a sign that your starter relay has started to develop issues.

The point of no return, however, is when you switch on your ski to hear one of two sounds: a click or a thud.

The major difference between a starter relay issue and a battery issue is that a weak battery will cause a continuous clicking sound while the starter relay only creates one click, then silence.

How to Fix It

Unless you have a lot of experience with your PWC, give this job to the professionals.

While the starter relay replacement itself is not a difficult thing to do, the positioning of the relay is awkward in some models and may be difficult for the amateur mechanic.

If you do choose to replace it yourself, preferably get the starter solenoid from a local dealer you can trust. It can be ordered online as well, but getting authentic parts is important.

While cheaper parts may work just as well, their longevity cannot be guaranteed. 

Depending on the model of your personal watercraft, replacing it may be easier. Just make sure you disconnect the battery first before proceeding any further.

Spark Plugs

Due to the nature of PWCs, which suffer a lot through being out on the water and in the sun quite often, spark plugs can take the damage from of the gas and oil combination in a different jet skis in different degrees.

Owner manuals should come with a detailed maintenance plan that discusses spark plug changes, so it is best to follow that (source).

How to Tell

Spark plugs suffer from general wear and tear on a PWC. It is recommended that you change them once or twice a year or every 25-30 hours used (whichever comes first) and keep extra spark plugs on hand in case of emergencies.

How to Fix It

To change spark plugs, complete the following steps: Loosen the plug and use the ignition coil to lift it off. Apply some anti-seize lubricant to the new spark plug, such as Loctite 767. Read our full step by step here.

Replace with new plugs and do not overtighten them. A good rule of thumb is about a quarter-turn of the plug once it makes contact (source). 

Starter Motor

This is less likely to be an issue but if the battery and starter relay are fine, it may be a problem with the starter motor itself.

How to Tell

If the display is working, the battery shows a full load and a sound like a wheel turning emerges, it may be a sign that the starter motor is down.

It is best to get a shop to look at it and confirm the problem. Sometimes a click or thud can also indicate the same issue.

How to Fix It

Depending on the model of your PWC, this should also preferably be done by a professional. However, if you feel like you have the expertise to do this yourself, take note of the following steps.

Once again, refer to the manual when attempting anything like this at home.

Generally, you would begin by removing the seat and the intake silencer. Depending on the model, you may have to remove the engine, and it is highly recommended that this is not attempted by amateurs. 

Disconnect the battery cables negative terminal first, and then continue by removing the positive cable on the starter motor. 

Remove the retaining screws around the starter motor and slowly jiggle the starter motor until it comes off. Before installing the new starter motor, clean any points that make contact.

On the O-rings of the new motor, grease with Isoflex (a lubricating substance).

Attach the new starter motor using the same steps used to remove it, using the retaining screws and torquing them to the level stated in your manual.

Carefully reconnect the cables on the starter motor and then the cables on the batteries, and you should be good to go.

Jam in the System

Since no one is using a PWC in a pool, there’s a good chance that, at some point, your ski will suck up debris from ocean or lake water into the system. We’ve all been there.

From seaweed to floating trash to driftwood to rocks, any of these foreign items could cause cavitation in your machine.

How to Tell

Cavitation occurs when water pressure drops quickly in an area (source). This is likely to happen when something interrupts the impeller flow in a PWC, causing deceleration. 

If you notice quick deceleration, a lot of vibration, a clunking sound from the back of the engine, or any kind of smoke emitting from your Sea-Doo, that generally indicates that something has gotten jammed in the motor. Shut the ski off immediately.

How to Fix It

Avoidance of shallow and debris-filled areas should be attempted as much as possible, and if you do find yourself in an area like that, speed through it as fast as possible.

However, if you detect cavitation or any of the above signs taking place, then stop the engine immediately and get ready to swim. 

Pull the key out, and get into the water. Approach the back of the Sea-Doo and carefully pull out the anything trapped in the intake. Be very careful to try and pull it out whole and avoid leaving pieces inside. Don’t injure your hand on sharp objects. Go slowly.

There may still be vibration and cavitation even when there is nothing blocking the intake. If you have swum to your PWC and cannot see anything solid in the intake, there may be another blockage elsewhere. 

In this case, avoid starting the motor again and have your ski towed to shore. Roll it on its side or winch onto your trailer. Look at the area between the prop and wear ring; There might be debris that is jammed in there.

Once your machine is back onshore, use a metal rod or ruler to free the blockage. Do this very carefully so as to not bend the impeller blades or damage the wear ring, or you will cause other issues and/or decrease performance.

Similarly, if something like old netting gets tangled into your shaft, take the Sea-Doo back to shore and remove the item. You may need to remove your grate if the cords are twisted too deeply. 

Unfortunately, if you hit rocks while riding, they may have caused more permanent damage and depending on the extent, might require replacement parts. In that case, please see your local dealer for quotes.

Grab a shop manual from eManualOnline below for your model PWC if you plan on a lot of DYI.

DIY like a pro! Shop from over 1,000,000 Repair Manuals at! As low as $14.99 per manual. Shop now.

Further Troubleshooting Tips

While the above should help you with the most basic and common problems, there are always solutions to other less common problems and situations with your Sea-Doo.

Starting a Sea-Doo That Hasn’t been Used for Years

There are a few things to look out for when starting a Sea-Doo or any other PWC after years of sitting. Preferably, get a mechanic to look over the craft before you begin. You can look at it yourself if you have the knowledge.

There are certain things to look out for before starting. The first one would be flushing out old fuel and oil since they are not viable after too many years in storage.

Check on the battery to make sure that it still has charge and make sure there are no liquids leaking from anything.

If the craft wasn’t properly winterized, you may have to check for cracking and rust. Spark plugs should definitely be changed if the PWC has been stored for more than two years. 

There is also the possibility that, in older models, the carburetor may need to be rebuilt if the jet ski was stored with gas as gas will turn to lacquer if left for too long and pouring in new gas does not make a difference at this point.

Newer skis may have fuel injector line clogging. These lines may also have to be replaced or at least cleaned.

Once you have run all these basic checks and made the changes, you should be good to go.

Abandoned jet ski on a beach with plants growing out of it

Starting a Sea-Doo after Winterization

Generally, the owner’s manual provides instructions on how to winterize your Sea-Doo (Storage and Pre-Season Preparation section) and, if these instructions are followed, your Sea-Doo should stay safe and sound for the season.

Another option is to allow your local dealership to winterize your PWC for you.

However, getting your Sea-Doo going again after the season should not be an issue if it was properly winterized.

You may have to start the machine a few times before it catches and starts to run smoothly, but this issue should only happen at the first start only. 

Once you have started your PWC, make sure you look and listen carefully to the machine. Any strange sounds, vibrations or lights on might indicate that the winterization wasn’t perfect.

For more information on how to move your jet ski from storage back to the water, read the article on “How to get your PWC out of storage.

Possible Solutions to Other Sounds Made by a jet ski

If you hear a whirring sound after you switch your ski off, it may indicate that the fuel pump or bilge pump (if you have one) is still running.

While the bilge pump may continue running for a few minutes after you switch off the PWC, and is considered perfectly normal, the fuel pump should not be running.

In a case like this, check to see if the relay is staying on or if there’s a problem with the battery charge.

Some users have reported that their handlebars squeak when turned, which usually appears after about 5 hours of usage.

For most, the sound seems to resolve itself. For anyone who continues to have that issue, WD40 sprayed through a straw to the column can help stop the sound.

If you hear a clicking sound when turning your handle left or right, it may indicate an issue with the steering column. This can be solved by loosening the link between the steering column and the steering cable.

Final Thoughts

While personal watercraft enthusiasts might encounter the occasional problem, their PWCs are sure to bring you hours of fun.

Most issues can be resolved quite easily with a little bit of time, money, and patience.

All it takes is a keen ear and a good understanding of what “normal” is to catch any issues before they become too problematic or require additional maintenance.