Jet Ski Won’t Start – 5 Things To Try

You go out to your jet ski and put the key on, and it won’t start.

This can be super annoying, but the good news is that a jet ski not starting is usually an easy fix.

1. Check The Battery

Most of the time, it’s either a dead or a bad battery.

The obvious sign it’s a dead battery is when you put the key on, and nothing comes on. The gauge does not light up, or it doesn’t make any sound.

Another clue it’s the battery is when you press the start button, and you hear multiple clicks coming from the engine. That multiple clicking is the starter relay clicking on, but since there is not enough juice from the battery to keep it locked, it just clicks rapidly.

Charge The Battery Or Replace

If the battery is over 3 years old, just replace it. You can expect 3 to 5 years out of a battery if properly taken care of.

If the jet ski ran fine last season and now it gives you multiple clicks, try charging it first. The battery could have drained over the winter and needs a new charge. You want to use a charger that is 12 volts and does not exceed 2 amps. It can take anywhere from 4 hours to 24 hours to charge some batteries – don’t rush it – let the charger do its thing.

Amazon has 12 volt battery charger that will work here. (Amazon Link Ad)

If nothing comes on when you put the key on and try to start the engine, then replace the battery.

Charged Battery But Still Won’t Start

It’s not uncommon to charge the battery, and the charger says it’s fine, and the jet ski still won’t start.

It’s AMPS that start a jet ski, and battery chargers go off voltage when charging. So the charger may say the battery is charged, but it’s a phantom charge as it lacks the amps.

There is no recovering a battery like this, so you will need to buy a new battery.

Bought A New Battery And Still Does Not Work

This is super rare, but I’ve seen brand new batteries that are dead. I would take the battery back and have them load test it. Only a load test can determine if a battery is good or not.

If the battery is good, then we can move on to the other things you can try.

2. Starter Relay

Most of the time, it’s the battery, but in second place, I would put the starter relay.

It’s rare for a newer jet ski, under 3 years old, to have the starter relay go bad. The older the jet ski, the more likely the starter relay will fail, especially if it’s never been replaced before.

A starter relay is a wear and tear item, but there is no way to predict when it will fail. And replacing it too soon is not worth it because it can be random. It’s not impossible for a jet ski’s starter relay to never fail; and if it does, it will be random.

How To Know The Starter Relay Is Bad?

When you put the key on the jet ski and press the start button and hear only ONE click or thud, that is a starter relay problem.

The battery has enough power to flip the relay, but since something is broken in the relay, the full current doesn’t get sent to the starter, and thus the jet ski doesn’t start.

Usually, the gauges turn on, and everything seems fine when a starter relay is bad. But when you hit the start button, nothing but a single click happens.

Tip: if you have a Sea-Doo with a brown starter relay then for sure that is the problem. They replaced them with black ones that work a lot better.

The Jet Ski Clicks But Eventually Starts

An interesting thing about a bad starter relay is that it can be bad but sometimes start the jet ski.

If you have to hit the start button multiple times before the jet ski starts, that is a bad starter relay.

I’ve seen people have odd rituals to get the jet ski to start. Like putting the key on two times, press the start button 3 times and then hold on the 4th; if this sounds like you, you need a new starter relay.

How To Replace The Starter Relay

Before messing with the starter relay, make sure to disconnect the battery.

I’m not going to say it’s hard to replace the starter relay, but it can be hard on some models.

Here is a video on how to do it.

3. Check The Pump

Note: Make sure to disconnect the battery before checking the pump.

Since jet skis are direct drive, anything blocking the pump can stop the engine from turning over.

Something in the pump keeping the engine from spinning over can sound like a bad starter relay. You get the one-click but nothing moves.

Usually, with something in the pump, you can feel the engine try to move and the whole jet ski kind of shake.

This could also make the engine slow to turn over. Something is stuck in the pump of the jet ski and only allows it to move slowly. A dying battery can also make the jet ski slow to start too.

4. Blown Fuses or Relays

It’s rare, but you could have blown a fuse or relays inside your fuse box.

There are power fuses that are used for starting and powering everything. They’re in the fuse box, which is almost always near the starter relay or the battery.

I’ve seen fuses that look good turn out to be bad, so keep that in mind. It’s best to use a multimeter to test the fuses.

5. Hydro locked Engine

This is rare as it usually only happens to people who have flipped or sunken their jet ski.

If water has gotten into the engine, this can keep the pistons from moving and prevent the jet ski from starting.

What’s interesting about this one is that if you have sunk your jet ski or kept it flipped over for too long, you need to avoid starting the engine. If there is water in the cylinders and you go to start, it can bend and break essential parts as water doesn’t have as much give as air does.

Jet Ski Still Won’t Start?

If your jet ski still doesn’t start, you’ll need to take it to the dealership.

We’ve reached the point where you can check for obvious things.

You could have a bad ECM or some other ghost that we can’t trace unless you have the computer that the shops have to talk to the jet ski.

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