10 Reasons Why Your Jet Ski is Not Accelerating [And How to Fix]


Jet ski acceleration problems are usually caused by one of the following issues:

  1. Low RPM Mode is Active/Learning Key Used
  2. Clogged Jet Pump/Cavitation
  3. Engine Overheating
  4. Low Oil Pressure
  5. Spark Plug Issues
  6. Electrical Issues
  7. Wrong Fuel
  8. Clogged Air Filter
  9. Carb/Fuel Line Issues
  10. Faulty Throttle Lever

If you want to learn more about these issues and their remedies, this post is for you.

Without further ado, let’s drill into jet ski accelerating problems!

Typical Jet Ski Accelerating Problems

1. Low RPM Mode is Active/Learning Key Used

Many jet skis come with a “learning key,” which electronically limits the performance of the engine. If your jet ski doesn’t accelerate properly, make sure that you use the normal key.

Other jet skis feature “low RPM mode,” which is also known as ECO mode or SLO mode depending on the make and model.

For the best performance, make sure that these modes are not activated. You can expect the best acceleration in “Sport” mode!

2. Clogged Jet Pump/Cavitation

The most common reason why jet skis won’t accelerate properly is a clogged or damaged jet pump.

Jet ski pumps are prone to sucking up seaweed, rocks, ropes, and other debris from the water. In the worst cases, these objects (especially rocks) can damage the impeller or the wear ring.

All this damage can lead to cavitation, which robs engine power!

Thus, if you feel your jet ski lacks power, you should carefully clean and inspect the pump.

3. Engine Overheating

A jet ski engine can overheat due to many reasons, but if this happens the computer will warn you of the malfunction. In some cases, it can limit the performance or stop the engine completely to avoid more damage.

If your jet ski is overheating, don’t worry just stop the engine and wait until it cools down. But if it overheats regularly, it’s recommended that you investigate the cause of this malfunction!

4. Low Oil Pressure

If the sensors detect low oil pressure, the computer may also limit the jet ski’s performance.

If you read an error message of “Oil pressure warning,” you should immediately refill the engine oil. If this doesn’t solve the problem, it’s recommended that you not operate the jet ski.

This is because improper lubrication may end in a seized engine or other major damage.

Best practice is to take the machine to a repair shop as soon as possible.

5. Spark Plug Issues

Spark plug issues can also lead to bad performance on your jet ski. What are the typical spark plug issues on jet skis?

  • Deflective of fouled spark plugs
  • Incorrect gap
  • Incorrect heat range
  • Faulty ignition coils

Fouled spark plugs are quite common issues on 2-stroke jet skis. This is because improper gas/oil ratio can foul the plugs, especially at cold starts!

Besides spark plugs, ignition coils can also go wrong, which results in inefficient sparks.

6. Other Electrical Issues

Let’s face it, new jet skis feature a very complex electrical system. Just one loose connection can cause an acceleration problem on a jet ski, not to mention sensor and computer malfunctions.

As investigating these issues requires some special equipment (like diagnostic cables and software) you should take your jet ski to a service shop.

Even if you can read the fault code(s) at home, you probably won’t be able to fix these electrical problems yourself.

7. Wrong Fuel

An incorrect octane number or stale/contaminated gas can also cause poor acceleration of the jet ski. Make sure that you use fresh gas every time you hit the water!

If your jet ski has been stored for a couple of months without adding a fuel stabilizer to the tank, the fuel is probably stale and needs to be replaced.

Also, don’t forget that performance jet skis require premium gas. If you are not sure what type of gas your jet ski needs, don’t hesitate to check it in the manual.

Keep in mind that in many cases jets skis have malfunctions and show fault codes if you use a lower octane gas than required!

8. Carb/Fuel Line Issues

Don’t overlook the carb and fuel line. If you have a 2-stroke jet ski, the source of the problem is probably the carburetor. It can be clogged or just needs to be properly set up.

Besides the carbs, on older jet skis the entire fuel line is prone to aging. Keeping safety in mind, you can’t go wrong if you replace the hoses.

If you have a newer, fuel-injected craft, on these models you should check the injectors and the fuel pump. Just like the carbs on vintage jet skis, these parts are also prone to clogging or having other malfunctions.

9. Clogged Air Filter

Besides fuel, the engine needs a sufficient amount of air to run efficiently. But if the air filter is clogged, it will likely block the air, so it cannot reach the engine.

Therefore, you may want to carefully clean the air filter.

10. Faulty Throttle Lever

When it comes to jet ski acceleration problems, the throttle lever is often overlooked. However, if it’s broken, it also can lead to a high idle speed or various handling issues.

Besides the throttle lever, you may want to inspect the brake lever as well.

Jet Ski Vibration When Accelerating

If you feel your jet ski vibrating while it’s accelerating, it’s likely an impeller or wear ring issue. In most cases small debris stacks up in the pump or wraps around the shaft. Try cleaning the pump first, as removing the debris eliminate the problem in most cases.

If you cleared the pump but the vibration is still present it’s a clue that the impeller or the wear ring are damaged. Keep in mind that inspecting these parts is not easy, as you have to remove the impeller from the jet ski.

The worst-case scenario is if the pump has sucked up a big rock or rope, as it can cause a driveshaft to bend. But don’t worry, as this is quite rare!

Conclusion – Why is My Jet Ski Not Accelerating?

In a nutshell, the possible reasons why your jet ski is not accelerating are as follows:

  • Low RPM Mode is Active/Learning Key Used
  • Clogged Jet Pump/Cavitation
  • Engine Overheating
  • Low Oil Pressure
  • Spark Plug Issues
  • Electrical Issues
  • Wrong Fuel
  • Clogged Air Filter
  • Carb/Fuel Line Issues
  • Faulty Throttle Lever

The good news is that most of these problems can be fixed at home. If you try fixing it yourself, you must refer to your jet ski’s service manual!

Refilling the engine oil or replacing the spark plugs is not difficult, but if your jet ski has major malfunctions, it’s recommended that you take it to your dealer or a reputable service shop.

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