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Why Yamaha 25hp 4 Stroke Outboard Problems? – Troubleshooting Explained & Solutions

Troubleshooting Yamaha 4-Stroke Motor

Yamaha has one of the most remarkable lines of 4-stroke outboard motors on the market. If you possess one of these engines, you already know how strong and dependable they are.

So, you are wondering what are Yamaha 25hp 4stroke outboard problems?

You run the boat for about 10 minutes to the fishing place and then turn off the motor. At the time, you start the engine, it can be caused by a number of factors. First, the carbs may be repaired, or the compression on all three is 150. Additionally, plugs might become damp or overheated.

That was just a simple hint. We have a lot to talk about in detail. And we will also talk about the solution! So, read on.

Why Yamaha 25 HP 4 Stroke Outboard Problems?

Yamaha 25hp 4 stroke outboard issues

Most of the people who use Yamaha 25hp 4 stroke go through the same outboard problem. We will talk about here the problems and want we can do to solve the problem.

Problem 1: Heavyweight

The problem appears to have been the weight of 25hp. Well, the mercury also has a common 60 Hp 4  stroke issues which are completely different Well the weight forced the transom too low.

When you tried to haul you will see the lines back aft. It would have been alright if you had left the engine running. But because you will turn it off as water was able to enter through the exhaust.

So it’s either leave the motor running while hauling or tilt the machine up. Before stopping and bringing the crew weight forward as well. I believe that because two strokes are lighter, they are less prone to this issue. Another option is to use a higher transom and a longer shaft.

Problem 2: Not engaging or Turning Over

This one is another common issue. Sometimes because of the malfunctioning electrical system it doesn’t engage or turn on.

In that case, you have to take initiative regarding the primary fuse. This problem can be called the starter problem.

Problem 3: The side Engine is Sung

It seems very normal. But the side engine is sung is another major issue of a Yamaha 25HP 4 Stroke outboard. Resolving the issue check that all of the screws in your throttle linkage are on the starboard.

You should go through the carbs, fitted new plugs, and clean the fuel filter. And after that added a new Yamaha fuel line system. It will end in the tank with a brass 90 fitting. Then hose the clamp which is launched in 2006 at 25hp.

You should loosen the bolt that passes through the accelerator arm. The engine would rev up in gear, get on a plane, and then bog all the way down. Wait a few minutes, then return to WOT and bog down. Then thoroughly examined the engine and discovered a loose bolt. Blue Loctite was used to clean and restore the system.

Problem 4: Stall at low speeds or while trolling

When cruising at low speeds or while trolling, the 25hp stroke motor may experience hesitation or stall. This is especially common on older models with worn-out bearings. If the stall occurs while the boat is moving, it can cause a loss of control and even a crash.

To prevent this from happening, it’s important to keep your speed and distance from other boats under control. If you notice that your hp stroke is experiencing problems, it’s best to dock and have a technician inspect the engine.

Problem 5: Noise from the engine or gearbox

This can be caused by a variety of issues, from worn or damaged parts to incorrect oiling. If you’re noticing loud noises coming from your boat, there might be a solution available.

If the noise is coming from the engine, it might be time to replace the part. Depending on the model, this could involve replacing the piston, ring, or cylinder head. Gearbox issues can also lead to noisy engines but typically require more advanced repairs. In some cases, it may be necessary to replace the entire transmission.

How to Solve Yamaha 25hp 4 Stroke Outboard Problems?

Yamaha 25hp Outboard

Now, we will talk about the solution to this problem that people facing. It will help you understand the problem in the first place and fix it by yourself.

Solving Starter Problems

To resolve starting problems, you can follow a few actions. If it isn’t engaging or turning over, it might be due to a malfunctioning electrical system. Check the primary fuse on battery-powered versions to ensure it is not blown.

To begin, detach and remove the electrical cover. The fuse holder should then be removed using a pair of pliers. If you discover that the connection at the middle of the fuse is broken. That indicates if you have a blown fuse. You’ll need to replace it with one of the same wattages. Which is indicated in the owner’s handbook for your Yamaha outboard.

If there are no broken fuses, the next step is to examine the battery. Before removing the battery from its housing, carefully separate the negative and positive cables. Using a wire-bristle brush, thoroughly clean away any damage to the battery connections.

Clean out any remaining dirt with one cup of water and one spoonful of baking soda. When you’re finished, make sure to properly dry the terminals with a clean cloth.

You should replace the battery if it is damaged. If not, go ahead and charge it. Reinstall the battery and wires after it has been fully charged. Remember to link the positive first, followed by the negative. After that, you may try starting the Yamaha outboard again. If it still won’t start, you should have an expert examine the electrical system.

Solving Engine Related Problems

Engine Related Problems

There are certain maintenance measures you may do if your engine isn’t starting or functioning properly. First, inspect the fuel system and make sure that there is enough fuel. If the levels are low, refill it using the gasoline recommended for your model.

Examine the gasoline lines that link the Yamaha outboard motor. Also, check the Problems related to the Yamaha outboard fuel pump. If you discover any breaks or leaks, you should immediately stop using the engine. You’ll want to get this handled by a specialist as soon as possible. Inspect the engine oil levels as well.

Before replacing the oil filler cap and dipstick from the oil tank. Assure that engine is upright and level.

Wash the dipstick clean using a clean towel, then reinsert it and check the oil mark. If the level falls below the “L” mark, the tank should be refilled. Alternatively, if the level is higher than the “H” mark, use a syringe to drain.

The spark plugs are the final phase in your procedure. You may examine them by removing them with a spark plug wrench.

If they’re burnt or broken, replace them with the spark plug type listed in your owner’s handbook. You should also use a wire layer mask to validate. So that the spark plug gap is within the range specified for your model.

If required, use a spark plug gap tool to adjust it. When you’re finished, reinsert each spark plug and replace the caps.

Solving Motion-Related Problems

Vibration is another typical problem that you may need to tackle. Check the condition of the propeller first if you’re experiencing significant vibration. If you discover any damage, you must remove it and bring it in for repair or replacement.

Again, If there is no visible damage, the next step is to remove any seaweed. Or other material that has been entangled in it.

Examine the driveshaft for breakage while you’re at it. If you discover any damage, you will need to get it repaired.

Finally, use a tool to tighten the motor mounting bolt and the steering pivot. Start the engine again to see whether the disturbance has subsided. If not, it’s time to bring it in for a checkup.


How long does a Yamaha 4-stroke outboard last?

Boat owners who practice regular maintenance will frequently inquire about this question. Yamaha manufactures a wide range of outboard motors. Most of the models have a lifespan of 1,500 – 3,000 hours. But depending on how frequently they are serviced, stored, and utilized.

Check out whose motors are better,  Suzuki’s or Yamaha’s and find out which one should you choose.

How can I tell if my Yamaha exhaust is corroded?

If you wish to undertake an examination, you must first remove the lower unit. Then, with a bright light, inspect the exhaust tube for severe corrosion or even holes. You’ll need an endoscope to look all the way up. You might not see it if you don’t know what to look for.

How frequently should your outboard motor be flushed?

A complete cleansing of the motors is required after each usage. And it is advised every six weeks if the machine has been sitting in storage. It’s critical to keep the motors running long enough for the thermostat to open. Enabling fresh water to flush the salt from the whole powerhead.

Bottom Line

I hope you got your answers about Yamaha 25hp 4stroke outboard problem. If you facing any of these problems I think you can identify them easily now. And also you can fix it by yourself if you are being patient.

But you can also ask for professional help anytime you want. You can also learn from them.

It’s time to say goodbye! Till then take care.

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