How to Start a Jet Ski That Has Been Sitting

The sun is out, the water is warm again, and you’re ready to hit the water after a few months.  But your jet ski has been sitting idle all winter. Knowing the best practices to get your ski back up and running will make for a smooth transition back to the water, along with ensuring proper upkeep and maintenance for it to be ridden for years to come.

How do you start a jet ski that has been sitting? Whether it’s been a long winter, or you’ve taken a couple of years off from riding your jet ski; you need to take proper care when beginning to use it again. It will depend on how long it has been sitting, but chances are you will need some replacement parts, a thorough inspection for leaks or damage, and an intensive cleaning. 

If you used my recommended proper storage techniques and took good care of the ski before it was sitting, you will have a much easier time of it when it’s time to be ridden again. Taking the time and being meticulous in your efforts will be a savior down the line.

What to do Before Starting Your Jet Ski Back Up

After your jet ski has been sitting for an extended period, you won’t be able to just fire it back up and hit the water, as tempting as it will sound. Some steps need to be taken to get back on the water safely. These steps will also help preserve the longevity of the jet ski over time.

When we push any type of engine or motor too hard, no matter the vehicle or watercraft, it will not end well. We’ll go step by step to cover things that you will need to consider, items that may require replacing, and all of the variables that will result in getting you back on the water with a jet ski running at its fullest potential.

How Long is too Long?

There is a big difference between storing your jet ski over the winter in colder climates and letting it sit in your garage for five years because you haven’t been using it. In either case, and everything in between; much of the inspection and precautions should look the same. But there may be more to do, the longer it has been sitting.

With that said, it is a good idea to give yourself additional time to ready the jet ski before you plan to take it out. Don’t expect to be able to get it out of storage and ride it later that day. In some cases, you may be able to do that. But it shouldn’t be banked upon since you are unsure of the condition it will be in and if anything significant will need to be repaired or replaced.

So the longer it has been sitting, the more you will want to ensure the integrity of the watercraft. Allow yourself some time to make sure you will have it ready when the day comes that you plan to take it out. If you’ve been riding regularly, and your ski suddenly won’t start, check out my potential solutions here.

Inspection

I know this doesn’t sound like the most fun, but an inspection is precisely what your jet ski will need upon removing that dusty cover from it. As badly as we all want to just get back on the water, it is essential to take the time and ensure everything is functioning correctly. You’ll be inspecting it from top to bottom for leaks, punctures, corrosion, or damage of any kind.

Pay special attention to:

  • The Battery 

You will want to check for corrosion on the battery and the surrounding area. Even if it looks okay, this may still need replacing. But checking the appearance of it will be your first step. Always carry a compact portable battery jump box in your ski’s storage compartment. Check out the Tacklife T8 on Amazon. Perfect for small storage spaces.

  • Spark Plugs

Inspect them for damage and remove them so you can clean and access the cylinders to spray some penetrating oil in there.

  • Cylinders

The cylinders will need oil and a good wipe down, but also give them a thorough look through to make sure there is no damage.

  • Carb and Engine

Your initial inspection of these will be purely aesthetic to be sure that there is no apparent corrosion or structural damage. Later, we will talk more about some of the pieces of the engine that commonly need replacing. 

All of these items will need to be wiped down during your inspection as well. When you begin taking things apart, why not give your jet ski a good cleaning as well.

During your inspection, you also want to be on the lookout for any type of leaks. Look for cracks in the siding, a battery leak, or a puncture in. You want to be sure everything is sealed and tight. If you discover anything has been punctured, it will most likely need a full replacement.  First, talk to a dealer who services jet skis.  Maybe they can repair it for less.

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Draining the Gas

While it is smart to leave gas in the tank during storage, it’s not gas that should be used after you take it back out. The longer the jet ski has been sitting, the more important this becomes. For skis that are stored over the winter, adding a fuel stabilizer before storage can prevent wasting the gas in the tank. Let the motor run for a few seconds after adding to distribute it through the system. But gas that has been sitting in the tank for more than a year should be drained. 

Make sure you drain any gas that was left in the tank and fill it with new gas. This will help everything to run cleanly and efficiently. Old gas will cause the engine to not run at its highest performance level. You may be able to use a stabilizer to help give it some of its punch back, but that is not the ideal solution. Be sure to safely dispose of the drained fuel to keep our waterways and oceans clean.

The other issue with gas that has been left sitting for long periods is possible damage to rubber seals. Gas sitting for that long will deteriorate the seals.  So drain the gas before you store the jet ski, right?  If only it was that simple.

Hopefully, you didn’t drain all gas before storage. With all of this talk regarding gas and why it shouldn’t be used if it is old, you are also probably wondering why we leave any gas in there when it’s just going to be sitting there. 

The reason you should still fill your gas tank before putting your jet ski away is to limit the amount of air space left in the tank. If there is only a little gas at the bottom of a tank it allows too much air space that can draw in moisture.  This moisture can cause problems when you are ready to start it back up. This can not only cause performance issues, but also long term sustainability problems.

Pro Tip: For gas tanks that haven’t been sitting for too long, you can use a can of seafoam help in stabilizing. If it has only been sitting for a few months and you just want to give the gas a little pep back to its step, this will usually be enough to do so. Only use this technique for gas tanks that have been sitting for a couple of months, though. For longer instances, go with a stabilizer.  

Keep it Clean

We talked a bit about the cleanliness piece during the inspection phase, but it is worth revisiting more in-depth. This becomes more and more crucial the longer the jet ski is sitting. By making sure everything is staying clean, you are helping ensure that no corrosion or damage is being done while it sits in storage.

When you go through your inspection and take apart any pieces, it is the perfect time to wipe everything down. If you are planning on storing the jet ski for a longer time, it can even be wise to give it a quick cleaning now and again as it sits in storage. 

These are all steps that will not only save you time when you take it out of storage, but it may also end up saving you money for new parts that will now last longer.

Replacing and Repairing Parts

Hopefully, after your inspection, you will find that nothing needs any significant repairs or replacements. But chances are, depending on the length it has been idle, you may be looking at a few parts that will need some extra attention.

Here are a few items that are good to keep in mind, as they may need replacing:

  1. Jet Pump

The jet pump may need replacing every 4 to 5 years or so as standard maintenance, regardless of storage. When you take the jet ski back out, you will want to ensure the pump and impeller inside the pump are in good working condition. That impeller is a vital part of the pump’s functions in accelerating water pressure before it discharges through the rear nozzle. 

Storage can be tricky for the pump because the main reason for underperformance or damage to it will have to do with debris that slowly but surely chips away at all pieces of the pump. So if it has been sitting for a long time, this is an essential piece to clean.

  • Fuel Lines

The fuel lines are sometimes forgotten about when considering items that could be affecting your engine performance or failure. The fuel stabilizer that we mentioned that will help the gas’s performance will also help in the maintenance of the fuel lines themselves. 

The job of the stabilizer is to increase performance and maintain an efficiently running system. So when you use it in your tank, it also helps to keep everything moving smoothly through these lines. Therefore, it will help in avoiding possible repairs or replacements for the fuel lines. 

If you see any corrosion, cracks, or blockages in the fuel lines, you will most likely need replacements.

  • Battery

Just like in our cars, if the engine won’t turn over, it is a pretty good indicator that the battery may be the culprit. If you live in a cold climate and have your jet ski stored for the winter, this is a common item that will need replacing. The cold weather will slowly draw power and contribute to the battery losing its charge.

An excellent way to keep it safe is to follow my recommendations and store the battery separately in a warmer location where harsh conditions won’t be able to negatively affect it. Just like any battery, it will eventually run out and need replacement. But with proper storage and care, you can extend its life. I’ve used the Battery Tender Junior for years.

  • Engine Seals

If the sealing has been compromised, you can bet on lower performance and a shorter life for your jet ski. Gaskets tend to be the most common form of seals for jet ski engines, and making sure you have the proper material for your gaskets will help in their lifespans. 

Many will recommend metal seals to withstand extreme conditions and if an engine will be in storage for extended times.  Obviously, metal will be slightly more expensive.  But if you spend a little more upfront, you do not need full replacements as frequently. 

  • Crankshaft

Rusted crankshafts are an all-too-common issue in jet skis, especially ones that were not correctly stored. Constant debates are going on among enthusiasts and users going through a rebuild, regarding the best type of crankshafts between Welded and Unwelded. (Check them out here.)  Either type will still be exposed to the elements, and there is always a chance of rust and corrosion that will lead to replacement needs.

Unfortunately, these are not the only issues. There may be others that arise after you take your ski out of storage but these are five of the most common.  For more information on reasons your jet ski may not be starting, this is a great reference.

Precautions to Take Before Storing

Understanding the best practices before you start your jet ski is essential, but it is equally as critical to prepare ahead of time. The list of things you will have to do when you are ready to start it back up will be much longer if you don’t take proper precautions. 

 Here is a brief step-by-step guide that will help you as you store your ski:

  1. Fill the Gas Tank

We already spoke in depth to the reasons this is important and the damaging effects it can have on the engine and fuel lines. So be sure this is a priority when storing.

  • Get an Oil Change

Seems silly, right? Getting an oil change right before you won’t even be using it for a long time. But it will be worth it when you take it back out. An oil change, a fresh oil filter, and using synthetic oil will give it its best chance to start like normal after extended sitting. While you’re at it, go ahead and also lubricate any areas like the steering equipment or brakes to assist in corrosion prevention.

  • Drain Any Water

You want to be sure that all water has been drained from the engine and entire jet ski. When you put your jet ski on the trailer, position it so the stern is lower than the bow. This will help it drain naturally. If there is any remaining water, you can start the motor for quick intervals of 15-20 seconds and crank the throttle a couple of times. This will force anything remaining to come out. 

  • Remove the Battery

To help keep the battery from your list of items you need to replace, go ahead and remove it from the jet ski for storage. Place it on a towel or mat and be sure it is stored somewhere that will not endure extreme temperatures. Cold weather will greatly shorten the lifespan of your battery. 

Pro Tip: Have an automatic battery charger (options reviewed on our maintenance catalog page) on hand. But be sure it is in a secure area and is not near anything flammable. 

  • Antifreeze

This may not apply to everyone, but if you are storing it somewhere that will be impacted by extremely low temperatures, this should be on your checklist. Your owner’s manual should include information on winterizing and how to properly use antifreeze for your specific model. Don’t just try to wing this, as each different jet ski will have their own set of instructions for antifreeze usage.

Ensuring a Longer Lifespan for Your Jet Ski

Owning a jet ski becomes a part of your lifestyle. It’s a fun and exciting activity that will never get old. But it can also get expensive. It will get more costly if you don’t take proper care of it and overlook procedures during times of storage. So to keep your jet ski in peak performance, be diligent in the steps you take before storage. 

Once you get the jet ski back out, give yourself time to make sure everything is functioning correctly and make any adjustments needed before using it again. Taking all these steps will ensure a longer lifespan, peak performance, and a fun time out on the water.


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Tim Conner, M.D.

Tim Conner, M.D. started boating in 1974. He has been involved in recreational boating continuously since then. Dr. Conner has been active in boating and watersports safety education for decades. He rode his first jet ski in 1997, and rejoined the personal watercraft arena in 2012 with a Sea-Doo GTX 155, followed by 2 supercharged SeaDoos. Scuba certification came in 1988, and he and the family have traveled the world snorkeling and scuba diving for decades. The family has recently taken up paddle boarding. Click the photo for a lot more.

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