Why Your Jet Ski Won't Start After Sitting All Winter

29th Jul 2026

Why Your Jet Ski Won't Start After Sitting All Winter

You've waited months for the weather to warm up, uncovered your jet ski, backed it down the ramp and... nothing.

The engine cranks slowly—or maybe not at all. Perhaps it turns over but refuses to start.

After months in storage, this is one of the most common problems jet ski owners experience. Fortunately, it's often caused by a handful of issues that are relatively easy to diagnose.

Whether you ride a Sea-Doo, Yamaha or Kawasaki, here's why your jet ski might not start after winter and what you can do to get back on the water.

1. Flat Or Weak Battery

The number one cause of springtime starting problems is a flat battery.

Even if the battery was healthy when you stored the ski, it naturally loses charge over time.

Signs of a weak battery include:

  • Slow cranking

  • Clicking when pressing the start button

  • Blank display

  • Engine won't turn over

A fully charged battery should read around 12.6 volts before starting.

If it's several years old, it may simply need replacing.

2. Stale Fuel

Fuel begins to deteriorate after sitting for extended periods.

Old fuel can:

  • Lose octane

  • Form varnish deposits

  • Block injectors

  • Cause hard starting

  • Reduce engine performance

If the fuel wasn't treated with a stabiliser before storage, draining and replacing it with fresh fuel may be the best option.

3. Fouled Spark Plugs

Spark plugs can become fouled from previous running issues or prolonged storage.

Remove and inspect them for:

  • Carbon build-up

  • Oil contamination

  • Corrosion

  • Excessive wear

Replacing spark plugs is inexpensive and often restores reliable starting.

4. Corroded Electrical Connections

Saltwater and moisture are tough on electrical systems.

Inspect:

  • Battery terminals

  • Starter motor connections

  • Starter solenoid

  • Earth cables

  • ECU plugs

  • Fuse box

Clean away corrosion and ensure every connection is tight.

5. Fuel Pump Problems

If the engine cranks but never attempts to fire, the fuel system could be the culprit.

Listen carefully when turning the key on.

Most modern jet skis briefly prime the fuel pump.

If you don't hear it, check:

  • Fuel pump fuse

  • Relay

  • Wiring

  • Fuel pump itself

6. Starter Solenoid Issues

A faulty starter solenoid can prevent the starter motor from receiving battery power.

Typical symptoms include:

  • Single click

  • Repeated clicking

  • No crank

  • Intermittent starting

Testing the solenoid is usually straightforward with a multimeter.

7. Moisture In The Engine Bay

Even under a cover, condensation can build up during storage.

Moisture may lead to:

  • Corrosion

  • Poor electrical connections

  • Sensor faults

  • Damaged connectors

A quick visual inspection can often reveal signs of water damage.

8. Rodent Damage

It's more common than many owners realise.

Mice and rats love warm engine bays and often chew:

  • Wiring looms

  • Fuel hoses

  • Vent hoses

  • Insulation

Before starting your ski for the first time, inspect the engine compartment carefully.

9. Blown Fuse

A simple blown fuse can stop your ski from starting.

Check:

  • Main fuse

  • Starter fuse

  • Fuel pump fuse

  • ECU fuse

Always replace blown fuses with the correct rating.

10. Safety Lanyard Or Switch

Sometimes the simplest explanation is the correct one.

Check that:

  • The safety lanyard is fitted correctly.

  • The emergency stop switch operates normally.

  • The magnet (if fitted) is secure.

Without the safety system engaged, most modern jet skis won't start.

Spring Start-Up Checklist

Before your first ride of the season, always check:

✔ Battery charged
✔ Fresh fuel
✔ Engine oil level
✔ Cooling system flushed
✔ Spark plugs inspected
✔ Battery terminals clean
✔ Jet pump free from debris
✔ Drain plugs installed
✔ Steering operating correctly

Spending 15 minutes checking these items can save hours of frustration at the boat ramp.

Prevent The Same Problem Next Winter

The best way to avoid springtime starting problems is to prepare your ski properly before storage.

That includes:

  • Flushing after the final ride

  • Adding fuel stabiliser

  • Charging or removing the battery

  • Applying corrosion protection

  • Covering the ski properly

  • Performing a complete pre-storage inspection

A little preventative maintenance goes a long way.

Need Replacement Parts?

If your jet ski won't start after winter, Jet Ski Parts Warehouse stocks a huge range of parts to help get you back on the water, including:

  • Batteries

  • Starter motors

  • Starter solenoids

  • Spark plugs

  • Fuel pumps

  • Fuel filters

  • Ignition coils

  • Genuine OEM parts

  • Premium aftermarket replacements

  • Quality used OEM components

Whether you're servicing your ski or tracking down a starting issue, our experienced team can help you find the right parts for your Sea-Doo, Yamaha or Kawasaki.

Final Thoughts

Most post-winter starting problems are caused by a weak battery, stale fuel or neglected maintenance rather than major engine failure.

By working through these checks methodically, you'll often identify the problem quickly and be back on the water without an expensive repair bill.