If your Sea-doo, Yamaha, Or Kawasaki Jetski won’t start then check out these simple fixes to get you on the water again.
You don’t need any special knowledge to fix your electrical problems. 9 times out of 10 it will be an easy fix. So let’s check out some of the common problems that will stop your PWC from starting.
Table of Contents
- 1 Replace the Spark Plugs
- 2 Test the Jetski Battery
- 3 Tip-over position sensor
- 4 Throttle Position.
- 5 Earth or neutral wire
- 6 Sea-Doo Lanyard, DESS Post, and Start/Stop button
- 7 Bad Fuel
- 8 Jammed Impellor
- 9 Fault Codes
- 10 Conclusion
Replace the Spark Plugs
Your spark plugs can be worn or have water or oil in the spark plug coil. Remove each coil and take out the spark plug. If it is all rusty and dirty just replace it they are cheap.
You can check out the Sea-Doo 4tec spark plug removal guide here.
The spark plug coils can also go bad and swell up. If they are hard to insert you could have a faulty coil. It will need to be replaced. Check that the coil electrical connection point is secure and has not fallen off during a recent service.
Test the Jetski Battery
Often if your Jet ski turns over but won’t start your battery could be going bad.
How many volts is a jet ski battery?
A fully charged Jet ski battery should read 12.6 volts or above.
A good way to test a battery is to put a multimeter on the terminals and measure the resting voltage.
If you press the start button on the Jet-ski, measure the battery voltage again. It should not drop below 10v. The several hundred peak amps of current that the starter motor draws could pull the battery voltage down to a normal 10 to 12 volts temporarily. Any lower and you have a faulty or flat battery.
You could try starting it with some jumper leads from another 12v battery or use an emergency portable jump starter. Depending on where the battery sits on your jetski this could be difficult.
Put the battery on charge every 3 months the keep it in tip-top condition. Also, it is a good idea to get yourself an emergency portable jump starter just in case you get stranded somewhere.
I like to replace my Sea-Doo battery every 3 years, they get a hammering and can fail early.
How many amps is a jet ski battery?
Jet ski batteries can range from 10 to 30 amp hours depending on the size of the Jet Ski. Most common Sea Doo 4-Tec batteries are around 19Ah (amps hours).
Smaller two-stroke Jet skis can get away with a small battery such as a 10-15Ah battery whereas larger 300HP Jet skis may require 20-30Ah batteries.
Seadoo won’t start just clicks
This is a sure sign that the battery is low on voltage. The clicking you hear is the started motor solenoid trying to engage. Charge the PWC battery and try again.
If the Seadoo won’t start and just beeps once then this is usually a sign that the lanyard key is not on properly or there is a fault in the DESS post. We will go into thin in more detail further on.
Tip-over position sensor
Also known as a T.O.P.S, this could be stuck in the tip-over position. This protects the engine if the Jet-ski tips over. When the tops valve is first activated (putting the lanyard on) it is energized to get it moving.
If your tip-over protection sensor is bad the Jetski won’t start. You can pull off the TOPS sensor and clean the contacts. Measure the coil windings resistance using an ohmmeter.
These can be removed and bridged out but it’s best to check how to do this for your model Jet Ski in an emergency.
On some model jet skis, especially Sea-Doo if the throttle position is fully pulled in, the jetski will turn over but will not start. Sometimes the throttle gets corrosion on the throttle position sensor. It will need to be replaced.
Check that the throttle lever is free and moves easily. Some lube on the hinge will help free it up if the throttle lever is binding.
I do use the throttle position pulled in when I am doing a yearly service and all the plugs are out of the engine. It will turn the engine over and cuts the fuel and spark. If your jet ski turns over but has no spark then check the throttle position. It is a safety feature.
It can also be used as an anti-flood feature. Pull the throttle in and press the start button for a few seconds. It will clear out any unburnt fuel in the cylinders.
Earth or neutral wire
The main neutral wire is connected to the battery terminal as well as the engine. This could be corroded. Corrosion causes resistance and therefore a loss of cranking amps.
Remove the earth bolt from the Jetski engine and clean it up with some sandpaper. Tighten up the bolt and check for continuity with an ohmmeter. The resistance between the battery neutral and the engine earth should be less than 2-ohms.
I have repaired a few Yamahas with the jet ski turning over but not starting because of a corroded neutral wire.
Modern jet skis are equipped with anti-theft immobilizer keys. These are waterproof but occasionally they go bad. You should have a spare key or even a learner key, try that to see if your personal watercraft will start.
Sometimes the start key post will go bad. Check if there is corrosion on the post. Chean it and try again. These are simple to change out and are usually a two-wire job.
Also, check the start-stop button. These are waterproof but sometimes the rubber can deteriorate in the weather so try pressing in and out the button a few times to clear any internal corrosion.
Safety Lanyard Switch SeaDoo Testing
If 2 short beeps are not heard when installing the safety lanyard, disconnect the switch wires.
With the safety lanyard removed connect the test probes to switch Black and Black/Yellow wires. It’s an open circuit, there should be no continuity.
Connect one test probe to the White/Gray wire and the other test probe to the switch terminal. Measure resistance, it should be “0” ohm. Connect one test probe to the Black wire and the other test probe to the switch ring. Measure resistance, it must be close to “0” ohm.
Safety lanyard on the switch; connect the probes to switch Black and Black /Yellow wires. Measure resistance, it must be “0” ohm.
Jetskis often sit for 6 months at a time without being used. At the end of the season fill the tank with fuel and use a fuel stabilizer in it. Run the Jetski for a few minutes to get some new fuel into the injector rail. This will keep the fuel fresh longer.
Every month start the PWC up for 1 minute only. This will cycle the fuel around the injectors. When fuel goes bad it will turn to jelly. You don’t want this in the injectors or carburetor on older models.
You can also try squirting some starting fluid into the throttle body air intake port. If your Jet-ski fires up on starter fluid then you have a fuel issue. You can make your own starting fluid following this recipe.
If your fuel pump fails then you are not going to pressurize the injectors to get fuel to the motor. The fuel pump is harder to check but a device called the Candoo Pro can help diagnose the problem.
The fuel pump is installed inside of the fuel tank so it may need to be removed to replace or repair. The following video shows some troubleshooting tips and how to remove the fuel pump on a GTX 185 Sea-Doo.
If you are out riding and your Jet-ski suddenly stops check if you have sucked up a rope or another item into your impellor. This can jam the outlet shaft and stop the PWC engine.
Here is a post on Jet-ski acceleration problems and solutions. It is well worth a read on how to unjam your intake grade on your Sea-doo or Yamaha PWC.
All newer Jet-skis made within the last 20 years will have some sort of display that will let you know of problems with the jet-ski. Sea-doo has a fault code list that is very comprehensive and I use it often to diagnose faults on customers’ jetskis.
These simple tests will help you work out why your Yamaha or Seadoo cranks but won’t start. Most times it is just a flat battery but sometimes further investigations are required.
It is a good feeling to repair your PWC yourself. It not only saves you money from the mechanic but you learn skills to fix things yourself.
Let me know in the comments of any other reasons you have had that have prevented your PWC from starting up.
I am a qualified Industrial Electrician for the past 20 years and I love to share my knowledge on home repair and maintenance jobs.
I love fast toys like Motorcycles, Cars, Jetskis, Boats, and Computers so writing about them is easy. Working on them is fun.
To keeps costs down I do all my own mods, repairs, and servicing. These skills I want to share with everyone. DIY is a skill everyone can learn.