Why Won’t My Jet Ski Start? 15 Common Problems to Check

It’s early Saturday morning, and you head to the dock to meet your buddies for a long overdue fishing trip. As the sunlight peeks over the horizon, you launch your jet skis into the water. Everyone’s mounted and ready to go, and you turn the key and hit the start button.

Nothing.

Not a blip or a failed start, just nothing. So, what’s going on here? Why won’t your jet ski start?

The reality is that the jet ski might be dead and unresponsive due to several factors. How long has it been since your last service? When did you last use the boat? What’s your riding style? All of these elements play a role in the mechanical and electrical function of your PWC.

This post unpacks everything you need to know about troubleshooting a failed start. Whether you have a Kawasaki Jet Ski, Sea-doo or any other model, We’ll unpack the most common reason for start failures and suggest how to handle the problem.

1. Dead or Weak Battery

The first place to start is with the battery. The battery is usually the weakest link in the system, and it’s the most common reason for failed starts.

Most jet skis run on lead-acid or lithium-ion batteries. The lead-acid battery is more reliable, but it doesn’t have the same charges the lithium packs.Open the battery bay and check the terminals. If they are loose, tighten them and try to start the PWC again.

The battery terminals can loosen over time with the natural crashing of the ski in the waves. If you have loose terminals, then it might be the cause of your start failure.A battery will last around two to three years, depending on how you maintain it.

The water needs to be full at all times, and you need to check and clean the battery for signs of corrosion around the terminals every so often. If the battery is new and the terminals are tight, you’re probably dealing with another problem.

2. Starter Relay Malfunction

The starter relay sends the electronic signal from the battery to the ignition, bringing the engine to life. It’s common for these starter relays to malfunction or burn out, causing the PWC to fail at the start.

Unfortunately, you’ll only be able to source these parts from the dealer. The dealer also has the tools required to do the job, so it will cost you money for the replacement. If your jet ski is under warranty, the dealer will replace the part for free.

3. Intake Blockage

Look into the rear inlet to see if something sucked into the motor. Most Sea-Doo models come with an auto-flush function that allows you to free the debris from the engine. If the waste is substantial, it could prevent the turning over of the motor, resulting in a start failure.

To prevent debris from entering the jet system, we recommend keeping a minimum distance of ten feet from shore. It’s better to do a water entry to the beach rather than have the ski fail on you.

4. Faulty Alternator

The alternator charges the battery while the ski is in use. If you have a faulty alternator, it won’t provide a substantial charge to the battery. As a result, the battery starts losing charge and eventually fails.

The alternator is another expensive part to replace. Typically batteries fail at around the 200+ hour mark on most jet skis.

It’s an expensive replacement, and you’ll need to get an agent to handle the work. You might be able to find aftermarket parts available online.

If you know a good mechanic, they can fit it for you at a reasonable cost. Using a private mechanic will cost you less than taking the ski to the dealer. However, the issue is that you lose your dealer-approved service history.

It’s also important to note that if your ski is under warranty, sending it to private mechanics can terminate it. Installing aftermarket parts into the motor will also void the dealer warranty.

5. Faulty Start Button

Sometimes, the start button could be the source of the failure. This fault is less common than others in this review, but it happens.

If you switch on the ignition and the dash lights up along with the ignition lights, it means there is power going to the battery.

If you push the start button and nothing happens, it must be an electrical fault. It’s a good idea to start at the first point of failure, so check the start button to see if it’s in working order.

6. Blown Fuse

On occasion, something as simple as blowing a fuse could be the culprit behind the start failure. Before you start pulling apart the start button and head to the hardware store to buy a new battery, check the fuse box.

The fuse box is in different locations on the boat, depending on the manufacturing brand. However, you’ll find most of them next to the battery. Look at the top of the fuses using a flashlight. If you see any broken or blown fuses, replace them.

It’s a good idea to keep spare fuses in your storage compartment. They are small and light, and they come in handy when you blow a fuse in the middle of nowhere. Consult your owner’s manual to find out where the fuse box is on the ski and where the ignition fuse is located in the box.

7. Fuel Separation

How long was it since you last had the jet ski out on the water for a spin? If it’s longer than three months, the problem could be the gas.

Gasoline contains additives that keep the gas in its optimal blended state. When the additives start to fail, the fuel begins to separate.

It becomes a gooey, sticky mass that clogs up the engine and the fuel lines as the fuel separates. You’re likely dealing with separation if it’s been sitting in the tank for a while under the sun’s heat. You’ll have to take the jet ski to a mechanic to have them flush and clean the fuel system.

It’s fine to leave unused fuel in the fuel tank, but don’t keep it there longer than a month. If you’re the forgetful type, it’s best to drain the tank and bleed the lines after each use.

We get it, gas prices are steep, but the costs of cleaning out the fuel lines, replacing filters, and refurbishing the motor are far greater than the savings you make between fills.

8. Dirty or Malfunctioning Fuel Filters and Injectors

If using low-grade fuel or the fuel separated in your tank, it will clog the fuel filters. Fuel filters need replacing as part of your normal servicing routine every few hours. Injectors are also a problem, and they tend to clog easily.

If you run the fuel tank close to dry, you might suck up sediment from the bottom of the tank into the injectors, causing them to clog and run inefficiently.

You can get treatment additives and capsules that you add to the fuel to clean the injectors. If they are really dirty or clogged, you might have to send the ski to a mechanic for servicing.

9. Dirty Air Filter

The engine needs air to breathe. If no air goes into the motor, it will start and fail almost immediately in a desperate sputter.

It’s common for oil to build up in the air filter and clog the passage of air into the engine. However, if you service the ski regularly, the dealer or mechanic will change the oil, air, and fuel filters as needed.

10. Fuel and Oil Line Issues

The fuel lines and oil lines feed the motor the raw ingredients it needs to perform at its peak. However, if there are kinks in the lines, the damage will prevent the proper movement of oil and fuel between the tank and the engine.

When the engine isn’t getting any fuel, it will sound like it wants to start. However, the lack of fuel prevents the motor from turning over. Inspect the lines and replace them if you see any damage.

11. Fuel Pump Problems

The fuel pump sends the fuel from the tank to the motor. If it’s malfunctioning or broken, it won’t feed the engine with the fuel it needs to start.

When you switch on the ignition, it primes the fuel pump. In most models across all manufacturing brands, you can hear a whirring sound when you turn on the ignition. This sound is the fuel pump priming.

So, if you switch on the ignition and don’t notice that sound, it’s probably a fuel pump failure. Unfortunately, fuel pumps are expensive to replace, and you’ll have to have a dealer or mechanic fit them for you.

12. Worn Spark Plugs

If it’s been a while since your last service, your jet ski is probably feeling sluggish. Not adhering to the maintenance schedule handed to you by the dealer or the mechanic can result in the slow death of our motor and ski.

The spark plugs ignite the fuel, providing the power to move the ski. However, if the spark plug gap is too wide due to overuse of the plugs, they will burn out and fail. The engine management system will detect the blown plug and refuse to start.

As long as you’re maintaining your jet ski, you shouldn’t have to worry about worn spark plugs causing start failures. However, some manufacturing brands are better than others. Choose spark plugs from a reputable, high-quality brand to ensure the best performance for your ski.

13. Sensor Malfunction

Today’s modern engines come with plenty of sensors managing engine functions. These management systems rely on sensors for feedback about engine performance and running conditions. If any of these sensors malfunction, it could lead to a failed start.

Typically, the dashboard will let you know which sensor failed. However, in some cases, you might have to send the ski to the dealer for a diagnostics test.

14. Hydro Locking

Owners can “hydro lock” their jet ski by trying to flush it out the wrong way. When the engine hydro locks, the water can’t escape internally.

As a result, the engine sticks and can’t turn over. Unfortunately, you will need to send the ski to the dealership to fix the problem.

15. Poor Key Replication

If you have a locksmith make you a replica key, there’s a chance it might not work in the ignition. Locksmiths have varying degrees of experience and skill, and some do a better job at key replication than others.

New jet ski models come with “coded” keys that require special order from the dealer if you need a spare. These keys are only available from the dealer, and they cost a small fortune to replace.

Why My Jet Ski won’t Start – Key Takeaways

• The most common cause of a jet ski failing to start is a dead or weak battery.
• A blown starter relay is the second most common issue causing a failed start.
• Together, the battery and starter relay problems account for around 80% to 90% of all issues relating to failed starts.
• It’s rare for the electronic components or the engine or fuel lines to be the source of the problem.
• If the engine clicks when you turn the key, the starter relay is likely the problem.
• If you have to press the starter button several times to get the motor to respond, the starter relay is likely the issue.
• If you fitted a new battery recently, the chances are that it could be faulty. Visit a battery center for load testing or take it back to the retailer for testing or replacement.
• Never rely on the reading from the voltmeter when testing the battery. Rely on the load tester for the real reading. They are readily available online at an affordable price.
• If the new battery load test is fine, the failed start is likely due to electrical issues.
• If you can’t hear the fuel pump priming when you turn the key, another common failure point might be the issue with the fuel pump.