Why a WaveRunner Won’t Start or Accelerate [And How To Fix It]

It’s always a hassle when you attach the clip to the shut-off switch to try and start the engine, and… nothing happens.

Even if you take proper care of your WaveRunner, faults may occur. But don’t worry, as some of these malfunctions can easily be fixed.

Thus, you may want to know how to troubleshoot your WaveRunner yourself.

We at JetDrift have collected and listed the possible causes for a WaveRunner not starting or  accelerating, and how you can you fix these.

To diagnose the fault, you can find the official Yamaha WaveRunner fault codes here.It’s also very important that you refer to the owner’s manual every time you service or repair your WaveRunner. If you can’t find the cause of the fault, best practice is to take your craft to your dealer or a service shop.

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Why is Your WaveRunner Not Starting?

There could be several reasons why a WaveRunner is not starting. The simplest and most common fault is when the shut-off clip is not properly attached or the tank is empty. Other common reasons could be electrical issues like malfunctions with the battery, spark plugs, fuses, or wires. Gas can also be contaminated or gone stale over time, which can lead to a clogged fuel line and injectors. Your WaveRunner will also not start in case of a starter motor fault.

Beyond these typical malfunctions, there could also be many other issues with your WaveRunners of course. These fall into four main categories:– Your WaveRunner won’t start (starter doesn’t turn over).

– The starter turns over but the engine still won’t start.

– Your WaveRunner’s engine starts, but it stalls or runs irregularly.

– Your Waverunner doesn’t accelerate or reach its top speed on the water.

Let’s take a closer look at these issues and their possible causes one by one.

WaveRunner Doesn’t Start (Won’t Crank)

The first issue could be if the starter won’t even turn over. The possible reasons for this may be as follows:

1. “Lock Mode” is active. Solution: Select the Unlock Mode in the Yamaha Security System.
2. Shut-off switch issues. Solution: Make sure the clip is in place. Remove and install it again if needed.
3. Burnt fuses and loose connections. Solution: Many times WaveRunners don’t start due to burnt fuses, so replace them if needed.
4. Battery issues. Solution: As batteries are prone to discharging over time, you have to recharge your WaveRunner’s battery if you don’t ride it very often. Beyond charging you may want to clean the terminals with baking soda and make sure the terminal connections are tight. If your battery is aged or you haven’t stored it properly during the winter, it may need replacing.
5. Loose connections. Solution: Loose connections or damaged cables can also cause malfunctions. Carefully check all the wiring.
6. Starter motor fault. Solution: Another common reason why a WaveRunner won’t crank is a starter motor fault. Replace the starter if needed or take your craft to your dealer.

WaveRunner Turns Over but Doesn’t Start

If your WaveRunner turns over but the engine still won’t start here are some things that should be checked:Throttle and RiDE level faults. Solution: Never try to start your WaveRunner with a squeezed lever! Release the throttle as well as the RiDE lever and try starting the engine again. Another issue could be if the levers have malfunctions. Inspect and fix them if they are broken.

Spark plugs. Solution: Remove and inspect the spark plugs carefully, as they can be defective or fouled. Spark plug issues are a common reason why so many 2-stroke WaveRunners won’t start, especially if they are not in frequent use. This is because gas can evaporate from the carburetors, leaving the oil behind. The next time you try to start the engine, the extra oil in the carburetors may cause too rich a mixture, resulting in spark plug malfunctions.

Fuel. Solution: If your tank is empty just fill it up and try starting the engine again. If you haven’t ridden your WaveRunner for a couple of months the fuel can be stale, or even contaminated. Siphon all of the old fuel out and fill the tank up with fresh gas. To prevent such cases always add stabilizer to the gas before the off-season, or if you are not going to use your craft for a while.

Carburetor or fuel injection system issues. Solution: On 2-stroke WaveRunners carburetors can cause a lot of headaches, as you have to adjust them again and again. If your engine is fuel injected, you have to check the fuel pump, as it’s also prone to failure. Moreover, you should carefully check the entire fuel line.

Engine malfunctions. Solution: If the repairs mentioned above don’t help then an engine fault is suspected. First, try reading the fault code to determine the fault, or take the WaveRunner to your dealer.

WaveRunner’s Engine Runs Irregularly or Stalls

It’s always a good sign if you can fire up the engine! But sometimes when you do this, your WaveRunner runs irregularly or gets bogged down. Let’s see what the possible causes are and how to troubleshoot them.

Fuel issues. Make sure there are sufficient quantities of fresh gas in the tank, as stale or contaminated gas may cause various malfunctions. Another important factor is the octane of the gas. Keep in mind that using a different octane fuel than your WaveRunner requires can also lead to misfires, or in the worst case, serious malfunctions! Because of this concern, you have to always use the right octane fuel in your WaveRunner, which is clearly stated in the owner’s manual.

Spark plugs and wiring. If the spark plugs are fouled or defective in your WaveRunner, not only can they prevent starting but they can also lead to other malfunctions. Inspect and replace the spark plugs if necessary. Before you install the new plugs, make sure their type and gap are in accordance with the manufacturer’s specifications. Additionally, check the electrical wiring and the connectors. Sometimes it’s just a loose connection that is causing the problem.

Fuel injection system or carbs. Clogged injectors or carburetors can also lead to irregularly running engines. Inspect them and the entire fuel line. Without an adequate fuel supply, your WaveRunner won’t run properly.

WaveRunner Doesn’t Accelerate

Once your WaveRunner starts and runs on the hose properly, it’s time put it on the water. If you are lucky, it will run without any issues!

But if you feel your WaveRunner isn’t accelerating well or can’t reach its top speed, you need to investigate further.

If your WaveRunner is slow or it loses power, the possible causes could be:Wrong operation mode. Make sure you didn’t activate the “Low RPM Mode” on your WaveRunner.

Cavitation. Cavitation may occur if the pump is clogged or the impeller is worn or damaged. Check and clean the pump if needed. You may want to inspect the impeller and the wear ring, and fix or replace those if needed.

Engine overheating or other malfunctions. If your WaveRunner is overheating, this can also activate the engine speed reduction control. There could be many reasons why a WaveRunner overheats, so check the dashboard for fault messages and fix the existing malfunction within the shortest time. Best practice is that you tow your WaveRunner back to the dock with another vessel to avoid further damage. Try to read the fault codes and check the owner’s manual for further guidance.

Low oil pressure. If your WaveRunner doesn’t accelerate perfectly, this can even be caused by low oil pressure. Check the oil level with the dipstick and refill if necessary.

Spark plugs and wires. Check, and replace the spark plugs if they are defective. You may want to inspect the wiring as well for loosen connections.

Fuel. As already mentioned above, using the wrong fuel can lead to many issues. If your WaveRunner is slow, you should check the condition of the fuel. Make sure there is fresh and the right octane gas in your tank before you hit the water. If the gas in the tank went wrong over time due to the lack of a stabilizer, remove it and refuel with fresh gas.

Throttle lever. A damaged throttle lever may also be the reason why your WaveRunner won’t accelerate. If it’s broken, fix it or take your craft to a Yamaha dealership or service shop.

Air filter. Not just fuel and sparks, but sufficient air is also needed for the engine to function properly. Clean or replace the air filter on your WaveRunner for proper performance.

Conclusion

There could be many reasons why a WaveRunner won’t start or accelerate. Here is the list of the most common issues with their possible causes:The WaveRunner’e engine won’t turn over at all:– Lock mode selected

– Engine shut-off switch: Incorrectly attached clip

– Electrical malfunctions (battery, connectors, fuses)

– Starter faulty

The engine cranks but slowly:– Weak battery

– Loose connections

– Starter faulty

The WaveRunner turns over but won’t start:– Damaged throttle or RiDE lever

– Fouled or defective spark plugs

– Burnt fuses

– Fuel issues

– Engine malfunctions

– Clogged fuel line and carbs or injectors

The engine runs irregularly:– Problems with the spark plugs or wiring

– Fuel issues

– Engine malfunctions

– Clogged fuel line and injectors/carbs

The WaveRunner starts but won’t accelerate:– Low RPM mode is active

– Clogged pump/intake

– Incorrect engine oil level

-Cavitation (damaged impeller/wear ring)

– Spark plugs

– Fuel issues

– Supercharger faults

– Clogged air filter

– Engine malfunctions

The WaveRunner is smoking:– Oil level is too high

– Damaged head gasket

– Water in the gas

– Coolant leaking

– Engine malfunctions

– Too rich a mixture (in case of 2-stroke engines)

This is our short post on why a WaveRunner won’t start or accelerate. We hope it’s useful to you.

Also, it’s highly recommended that you always refer to the manual before you start servicing your WaveRunner yourself!

If troubleshooting fails, best practice is to take your craft to a dealership or a reputable service shop.