What To Do If An Outboard Has Been Sitting For Awhile!

Things in life happen and there are many different reasons why a boat ends up sitting around. Sometimes for a seasonal year, sometimes for 5, 10, or even 15 years! What Should You Do If An Outboard Has Been Sitting For Awhile?

  • Remove the Spark Plugs & Oil The Cylinders, Replace Plugs if Needed.
  • Check the Condition of the Gear Lube.
  • Disconnect the Fuel Line From the Boat & Check the Condition of the Fuel.
  • Connect a Separate Fuel Tank with Brand New Fuel.
  • Check the Oil Level or Fill the Oil Injection Tank.
  • Connect To a Fully Charged Battery.
  • Start and Run the Engine on a Garden Hose.

These are the basic checks that should be performed if you are planning on taking a boat out of long term storage. Or, are reviving an engine that has been sitting for years. Here are the details that you need to know.

Removing the Spark Plugs & Oiling the Cylinders

Boat has been sitting for 10 years

Before getting wild and trying to do anything with an engine that has been sitting for a long period of time. It’s best to remove the spark plugs. 

This will show us something about the engine, like what is going on inside of it. Looking at the spark plugs, for rust, corrosion or any other kind of water damage. That way if need be,

we can get some fresh plugs into it. This avoids any kind of issues that can be caused by some old nasty, rusty spark plugs! 

With the spark plugs out of the cylinders, we can take some fogging oil and squirt it into the cylinders. 

Then turn the engine over a couple of times by hand and get the oil around the pistons and the rings.

Getting everything nice and lubed up. So that when the engine does start, it won’t be running on dry cylinders and possibly scoring the cylinder walls, or messing up a piston ring.

Checking the Condition of the Gear Lube

boat has been sitting for 5 years

The next order of business is to check out the condition of the gear lube. We are looking for water. 

Making sure that there is good gear lube in the lower unit will also play out in our favor when it is time to get the boat and motor back into commission on the water. 

Seeing that there is no warning for when a lower unit is about to blow up; this is the perfect time to get this out of the way. 

Gear oil is lighter than water, so if there is any water in the lower unit, it will be below the oil. Right where the drain plug is. 

When we remove the drain plug, if there is any water, it will come pouring out before the gear lube. Then if there is water, we want to make sure the lower unit shifts in and out of gear properly. 

Then, fill the case back up with some fresh, brand new gear lube, and a couple of new seals on the drain and vent plugs. (For more information on Gear Oil and What Color it Should Be, Check out this article we wrote about that)

Disconnecting the Boat Fuel Line & Checking the Condition of the Fuel

With oil in the cylinders, good spark plugs, and clean gear lube, it’s time to get serious! Fuel! When fuel sits for a long period of time. It loses its octane.

Then, depending on what kind of fuel was left in there; there could be a lot of water in the tank. 

Also, depending on what kind of additives have been put in the fuel, it could be sludgy, slimy, or have sediment in it! It’s best to avoid running any of that junk into the engine.

What we can do is find a good place in the fuel line close to the engine, and disconnect the fuel line from the boat to the engine. 

Makes sure that the boat has the bow lifted into the air. Any water or dirt that is in the tank, will be shifted to the back of the tank and pulled out of the pickup tube first. 

If the bow is down, then there could be water in the tank, but just shifted to the front of the tank, where you couldn’t get to it.

Then, if you finish getting the boat ready, and take it out; the first time you get on plane, the water will shift to the back and the engine will suck it all up and you’ll be dead in the water!

Floating off into another wonderful lesson, via hard, real-life experience! (And no one wants this) Once you have good fuel, we’re getting so close to the water you can almost smell the salt!

Connecting a Shop Fuel Tank

Buying a boat that has been sitting

If the fuel is not usable, then we’ll need to connect up to a shop tank that has fresh, brand new fuel in it.

Where we disconnected the fuel line, we can just splice the fuel tank into the fuel line going to the engine using the primer bulb. 

This way we can prime up the fuel system when we are ready, and even push the clean fuel to the engine, pushing out all the old, bad fuel.

Draining the Engine Fuel

We don’t want to forget about the fuel that could be left in the engine though! We’ll want to drain that out next. 

We can do this by figuring out whether you have a Carbureted engine or Fuel Injected Engine. The process is basically the same for both, with only one difference. 

If you have carbs, then all you need to do is unscrew the drain screws on the carbs.

Just until there is a little fuel coming out of the screw, don’t unscrew it all the way or you could drop the screw! 

Then using a primer bulb on the shop tank, (If you had to use one), prime up the bulb until there is fuel pouring out of the screws.

Pushing all of the old stuff through the lines and out the carbs. Those carbs could give you problems before this is all over with, but that is a whole other subject.

You will just need to remove them and clean them out if the engine won’t start and run properly. 

Then for the fuel-injected engines. Locate the VST, (Here’s an article about VST’s and FSM’s!), and on the bottom of it, there will be a drain screw. Some even have a drain tube on it as well. Same deal, unscrew it a little until the fuel comes out.

Then prime the bulb until clean fuel comes out. (There is a lot more fuel held in the VST, so having a container to catch the fuel in is definitely a good idea!) 

Some VST’s have a vent plug or a Schrader valve that you can press in to let air into the VST to replace the fuel that is coming out.

This allows you to get all of the fuel out of the VST and replace it with the brand new fuel.

Checking the Oil Levels & Condition

Depending on if you are working on a 2-stroke or a 4-stroke, it will dictate what you want to do here.

If you have a 4-stroke; making sure that the oil level is where it should be is something that needs to be done prior to firing up the engine.

You don’t want to run the motor when it is low on oil. This is also an opportune time to change the oil if it is really old and dirty.

Or just make sure that the oil is in good condition. On the 2-stroke, we want to make sure that the oil injection system is full.

When we are talking about taking a boat that has been sitting for years, it’s hard to say what has happened during those years it was sitting. I’ve seen all kinds of weird stuff that you would never think could happen, happen.

An example of this; one time someone came down to get their boat out of storage that had been at another marina for a couple of years. When they got here, one engine wouldn’t start! So, they brought the boat over to get it checked out.

When we got the boat and pulled the cowling off. The sight was unbelievable! Someone had stolen the entire powerhead off the engine! The whole thing! Wire harness and everything else! Gone!

So, you never know what you are going to find when dealing with a boat that’s been sitting. So make sure all of the oil reservoirs are full!

Making Sure the Battery is Fully Charged

How to start a motor that has been sitting for years

As we get closer to starting the engine, we are going to need battery power! It is extremely rare for a battery to hold a charge when it sits for an extended period of time. Before firing up, we’ve got to have power!

A lot of times the batteries will need to be replaced. Or at the very least, charged up.

Before scrapping the batteries; go to the boat a day or two before you plan on doing the whole operation.

And just stick a battery charger on the batteries. If there is more than one battery, put the battery switch to all. Make sure everything is off.

Then, just leave the battery charger on a trickle charge of 2 or 10 Amps.

Depending on the time you are going to leave it there. If you have a couple of days. Put it on the 2 Amp. If you only have one day, put it on the 10 Amp.

Leaving the battery switch on “both” will allow the battery charger to charge up both batteries over the time you leave it on there.

***Remember that chargers could cause fires! So be careful where you leave the charger and how you hook it up! Make sure it is properly attached to the battery and that the cord and cables are not laying on a pile of dry leaves! Or anything else that could catch on fire!***

Running the Engine on a Hose

How to start an outboard motor after stoage

At last! The moment has arrived! It’s time to fire that engine up! Get some water to the engine via a garden hose. Then put on some ear muffs and let the water run for a couple of seconds.

Prime up the fuel, turn the key, and hopefully, start and run the engine!

If you are going to let the engine sit and run for a while, (which is a pretty good idea to do). I would advise using the earmuffs as opposed to the flush attachment.

There is absolutely nothing wrong with running an outboard engine using the flushing port on the engine. You just don’t want to rev up the engine and run it at higher RPM’s.

The main thing is that you don’t want to burn up the rubber impeller and you don’t want to overheat the engine.

So, running it for 10-15 minutes on a set of earmuffs on the lower unit is a good thing to do.

Shift the engine into forward and reverse. Make sure that everything is working. The trim, the steering, the shifting. That way there are no surprises when the boat goes into the water.

The steering is a pretty important thing to check! Especially on a boat that has been sitting for a long time.

Mechanical steering cables like to lock up at the motor, and you don’t want to find out that it is locked up when you are fresh off the trailer, floating farther and farther away from the dock!

What To Do if the Fuel is Bad?

In the event that the fuel in the tank is bad, you are going to have to get that fuel out of the tank. DO NOT JUST PUT FRESH FUEL ON TOP OF IT! Look at it this way. If you have 30 gallons of bad gas that is absolutely not burnable.

Then you put 30 gallons of brand new gas on top of it! What do you have then? If you have half a glass of spoiled milk, and you take some fresh milk and pour it in on top of it. What do you have then? Are you going to drink up?

(Normally the answer is no, but when put to the test, you never know!) The same goes for your outboard.

Opposed to not running at all on the bad gas. It might just run extremely poorly on the half and half mix! It’s best to just get rid of what you have and cut your losses.

Save yourself the heartache, pain, suffering, and trouble of messing with the engine after sucking up a bunch of bad gasoline. The best thing to do is to go down to the local auto store, Napa, Autozone, Advanced Auto, or whatever you have.

Buy the cheapest fuel pump they have, a $20-30 pump that attaches to a 3/8″ hose or 5/16″ hose, whichever is in your boat.

Then, depending on how much gas is in the boat. Pump it into some 5-gallon buckets, or a 55-gallon drum.

Which can be disposed of by any local recycling facility, oil pump-out service, or hazardous waste facility. Don’t forget to tip the bow up and get all of the stuff out of the tank during the process!

How Long Can A Boat Sit?

How long can a boat sit without running

There is no exact figure for this type of question. If a boat is properly serviced, winterized, or summarized. Then it can theoretically sit indefinitely depending on the location.

Now, if the boat is out in the weather, and hasn’t been properly prepared for long term storage, then it might not last very long.

If there is water in the lower unit and it is put away in the North during winter, the water will freeze and crack the lower unit.

Destroying it! If it’s put away down in the South, same circumstances. Then the gears and bearings will rust and corrode, failing when it is put under a load and ran hard!

If it’s sitting out under a tree and filling up with animals, making themselves their own standing Carnival Cruise; then, the boat will begin to rot away pretty quickly.

The moral of the story is, that you should properly perform the right procedures before putting your boat away for any period of time. That is if it is going to be during winter or for more than 6 months.

Buying a Boat That Has Been Sitting

If you are looking at buying a boat that has been sitting for a long time, you should perform all of these processes, plus a couple more. You should do a spark and compression on the engine.

Then you should check over the boat. Look at these main points. The fuel tank, the hull, the stringers, and the transom. You want to make sure that all of these check out and are in good working condition. Not rotting or falling apart!

Here is a great article we wrote about “Things You Should Know Before Buying a Project Boat!” We give a lot of really insightful tips on things that you are going to want to go over before buying it. Especially it if has been sitting around for a while!

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Aaron Hilligoss

Aaron has been working in the Marine Industry for over a decade and holds certifications for Yamaha and Mercury Marine. It is not uncommon for him to own and be working on at least three different boats at any given point in time!

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