Common Yamaha 115 4-Stroke Problems (& How to Fix Them)

Yamaha 115 4-Stroke Problems & How to Fix Them
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Wondering what potential problems are most common for 115HP Yamaha 4-Stroke and how to solve them?

This quick guide will cover all of the pros and cons of these motors, common problems, troubleshooting and how-to’s for fixing them.

Generally, the Yamaha 115 4-Stroke is one of the most reliable, versatile, and efficient outboards available for mid-range boats. No motor is perfect, but this motor is known for being one of the most problem-free options on the market.

First released to great acclaim in 1999 it immediately impressed boating enthusiasts, quickly becoming the go to choice for all mid range sporting and fishing craft from among the F-Series motors that range from 2.5 Horsepower up to an incredible 350 Horsepower.

Despite the solid reputation of its first design, Yamaha went above and beyond the call of duty by upgrading the motor in 2014, improving on the intake and labyrinth exhaust systems allowing it to deliver even better performance while simultaneously suppressing noise levels.

The entire Yamaha F-Series range of outboard motors are beautifully designed and engineered with precision and a serious attention to practicality and power. This gives you market-leading performance with (ideally) few technical or engine problems over many years of use.

Yamaha 115 4-Stroke Pros And Cons


  • Massively reliable outboard motor that you can trust to have your back in the water
  • Flexible warranty that can be transferred to future owners if you choose to further upgrade or sell your motor
  • Explosive power and unbeatable performance
  • Easy to maintain and service, which helps to extend the motor’s working life
  • Amazing fuel economy that provides excellent value for money
  • The electric fuel injection system perfectly measures the fuel to optimize engine performance


  • At nearly 400 pounds the motor is fairly heavy for its category
  • The Yamaha 115 4-stroke is a little on the expensive side but its popularity speaks for itself

Common Yamaha 115 4-Stroke Problems & Troubleshooting

Dual Yamaha 115HP 4-Stroke Outboards
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Although Yamaha 115 4-stroke motors are superbly designed and well-engineered, you can still run into occasional problems. There’s not really any single standout problem with these engines though. The vast majority of potential issues are simple and easy to solve with the right practical knowledge.

Carbon Buildup

Yamaha has always been known for designing engines made to run hard at high RPM’s. The 115 4-stroke is yet another example of this.

Carbon buildup can be a potential problem if a Yamaha 115 is operated solely at low RPM’s. This is a minor potential problem and it can be solved by simply opening up the throttle and letting the outboard run.

Again, hardly an issue, but it’s definitely worth mentioning for anyone who is in the market for or currently owns this motor.

There’s Too Much Vibration

Another common Yamaha 115 4-stroke motor problem is excessive vibration which can lead to further issues with your motor. This is usually caused by the propeller which may have been damaged while you were out on the water. If your propeller is damaged then you should get it replaced before you take your boat out again.

There could also be debris from the water trapped in the propeller, such as plastic rubbish or seaweed that’s got tangled in it. If there is then just remove it before you start the engine. One the other hand, if your propeller is looking in good condition then just give the mounting bolts of the motor a good tighten with a wrench to ensure that it’s properly attached.

Outboard height can also play a role in vibration. Take a look at our guide to outboard height to find out if yours is too high or too low.

If you still experience significant vibrations you should contact a professional to take a look for you.

The Starter Isn’t Engaging

Issues with the starter is a complaint that you may have with your Yamaha 115 outboard motor, with the engine not engaging correctly. This is usually a result of a fault in the electrical system, such as a blown fuse. If you’re having trouble starting your outboard then the first thing you should do is to unscrew the cover and then extract the fuse holder with electrical pliers.

Following the removal of the fuse you simply need to check to see if the connection in the center of the fuse is broken; and if it is, you’ll need to replace it with a new one.

Don’t forget to replace it with a new fuse that has the same amperage or it will immediately blow again. It’s always worth having a few spare fuses handy so you can quickly replace it without having to wait for a mail order delivery to arrive.

If you’ve checked the fuse and it’s still intact then you’ll have to check the battery next, which is the other most likely reason for having problems with the starter.

To safely replace the battery you should disconnect the negative and then the positive cable, and then using a wire brush you should clean off any corrosion or other debris that has built up on the battery terminals. You can also use a mixture of water and baking soda to give it a thorough clean, again, using your wire brush.

Once you’ve cleaned the terminals you should reconnect the cables, remembering to start with the positive and then the negative cables after carefully drying the terminals with a fresh towel.

After you’ve recharged the battery to its full capacity and replaced it in its housing, the engine should start with ease.

The Engine Is Not Starting Or Running Properly

Another issue that you might find yourself facing is that the engine is not starting properly or it’s running at a less than optimal level. This is usually nothing to worry about though and a few simple checks will generally root out the cause of the problem.

Firstly, you should give your fuel levels a quick check. If you find that you’re running low on fuel then you just need to give it a top up with the right gasolene for your motor.

If the fuel levels are okay then you need to check that the system’s fuel lines are not damaged or leaking. This is extremely important and if you find that your fuel lines are leaking or even slightly damaged then you should switch off the engine immediately and then contact a professional to get them repaired before you try to use your outboard motor again.

Next, if your fuel lines are intact and there’s enough fuel in the tank, you should check the oil levels. Make sure the engine is sitting in an upright position and then remove the cap from your oil filler.

Using the dipstick, check the oil levels and if you find that it is underneath the ‘L’ marker then give it a refill. On the other hand, if the oil is above the ‘H’ marker then you need to remove the excess with an oil syringe.

Lastly, you should check your spark plugs. Remove these, using a wrench, and check to see that they are not cracked or burnt out. If they are, you’ll have to replace them. If they look okay then give them a clean and reinstall them and you should be ready to go!

Final Recommendations

Most of the problems that you’ll face are very easy to fix and usually just takes a few simple adjustments, basic replacements of simple parts or a top up of fuel or oil.

However, it’s extremely important to remember that if you’re unsure about what the problem is then you should always contact a professional to give your motor a look over. This is because damaged fuel lines and other internal issues can be dangerous and so you always want to be 100% sure that your motor is working properly before you get out on the water.

However, as a quick glance through the customer reviews of the Yamaha 115 4-stroke outboard motor will tell you, they are a fantastic choice for boating enthusiasts; and with flexible warranties available and an excellent working life you’ll get superb value for your money.

All 4-stroke motors are are known for their compact sizes, great fuel economy, and outstanding versatility. The classic Yamaha 115 4-stroke outboard is definitely one of the world’s favorite models and an ideal choice for all sorts of runabout vessels, middle sized boats, bass boats (if you’re in the market for a bass boat, take a look at our list of current favorites), and bowriders; boasting the strength to reliably take on choppy ocean waters and even high waves.