Yamaha Outboard Not Pumping Water

Yamaha Outboard Not Pumping Water – 4 Reasons And Solutions


You bought a second-hand boat. Suddenly a malfunction shows up, that water is not streaming through the motor. And you are confused about how to fix it. 

So, you’re thinking, Why is Yamaha outboard not pumping water?

This type of technical issue occurs in any vehicle and that’s absolutely normal. There might be various reasons behind your outboard not pumping. Like clogged water stream fitting, the wrong direction of the impeller, the insufficient height of the water, etc.

However, this much information is not sufficient enough. We have got an entire article with 4 reasons and solutions for you to solve this problem.

So, let’s discuss the issue briefly-

Why Is The Yamaha Outboard Not Pumping? – 4 Ways to Repair It

Rather than calling a technician, you can solve any of these problems by yourself. If you have minimum technical knowledge. 

We have found 4 problems and given a proper solution to each of them.

These might help even when you have issues with your Yamaha 300 outboard.

Don’t worry, you got our back. We will help you to restore your motor in no time.  

Problem 1: Water Stream Fitting is Clogged 

There is a chance that your motor’s water stream fitting is clogged. Insects always try to crawl up into the outlet hole. Most of the time, they get stuck inside the hole and die.

You can find out if there’s dirt or not by moving the motor’s bottom cover. Then look into the water stream fitting.


To clean the clogged area, you need to follow two steps. These will help you to clean the dirt off in the easiest way. 

Step 1: Cleaning Dirt 

There is a water stream fitting located at the bottom of your motor’s cover. By poking a thin piece of wire, you can clear the fitting. Then pull out any debris or insects. 

In the same way, check out the cooling water intakes. Clear them out with a thin wire, if they are clogged as well.

In the meantime, you might be thinking about replacing your Yamaha outboard ignition switch. Just in case, it has been clogged by debris.

Step 2: Keep An Eye on The Lower-Rear Part

You need to connect a garden hose to the motor’s flushing point. Over the raw intake, you have to put the hose.

Turn on the water, start the motor and keep warming it to its usual operating temperature.

Stay alert while it’s heating up your outboard’s top cover.

Caution: You need to follow the safety measures while fixing the motor. Maintaining precautions saves you from any harm. Try to be more cautious while using the wrench. Unless you might get an injury. 

Problem 02: Insufficient Water Height 

Insufficient water height could be a reason as well. Less water can’t cover inlets, thus it prevents water from getting to the pump. As a result, it isn’t pumping. 

In the summertime, the sun evaporates the water from rivers, canals, and seas. Hence, your motor can’t pump water.


So, you need to place the outboard motor above 60 feet. You can take your boat to a big canal or a river or even to the sea. 

Then turn your motor on and check if the motor pumps water or not. This can even create issues with your 4 stroke Yamaha 115.

Problem 03: Telltale Placed to The Wrong Side

Another valid reason is, you are forcing water into the telltale in the back. Hence, the motor is unable to pump water.

If the telltale is misplaced, water can’t flow through the pipe. The motor gets stuck and becomes unable to pump water.


If you have set the telltale in the wrong direction, you need to detach that part. And set it in the forwarding direction.

With the help of a wrench, unplug all the nuts and bolts. Detach the telltale from the motor.  

Now take the telltale and put it in the forward direction. Then set all nuts and bolts once again. 

By now you have understood what will be the next step.

Exactly, you’re right. Turn the motor on and watch if it’s streaming water or not.

Problem 04: Impeller Is Damaged 

If any solution explained above doesn’t work for you, the problem is somewhere else. You have to understand that the impeller is damaged or worn beyond repair. 

Thus, it needs a replacement.


Before taking a determined decision about your motor, cross-check the outboard motor once more. This process will help to pick the proper decision.

We have explained the procedure down below-

Step 1: Inspect The Water Stream Fitting Once Again

Again, inspect the water stream fitting. You will get to know the impeller is working if you find water is pouring forth.

But turn off the motor immediately, just after you realize that no stream of water is coming through the motor’s cover.  

Now, you have understood that the problem is nowhere but in the impeller.

Step 2:Cut Off the Faulty Impeller

As we have identified the issue, it’s time to replace it with a new one.

Firstly, unscrew nuts and bolts which are attached to the lower unit with a thin-wall socket. 

Then, you need to untie the water pump by removing the bolts, using an adjustable wrench. Now, open the pump cover up then place it on the top of the driveshaft. 

Just similar to the pump cover, pull out the impeller and place of the driveshaft. 

Step 3: Insert A New Impeller

In this step, you will need to change the impeller. There are quite a number of impellers available in the market

In case you don’t know which impeller is best for your outboard, we have options. 

Product 1
Product 2

Now that you have your impeller, it’s time to install it.

Under the water pump’s cover, you have to insert a new gasket in the groove. Later, attach a bead of gasket sealer to the gasket. 

Lastly, put back the pump cover and impeller down further. Slowly move the driveshaft onto the pump’s faceplate on the lower unit. 

Finally, you’ll have your Yamaha outboard pumping water. In case, it still doesn’t work, contact a professional.


Question: Why is my Yamaha outboard not peeing?

Answer: Give a quick check to the thermostat. If it is clogged with salt or has been stuck, try vinegar flush as it removes the blockage.

Question: How could I know if my outboard water pump is bad?

Answer: If you find that the outboard motor is overheating or the impeller is living on borrowed time or there is a reduced stream of water from the cooling water outlet.

Question: Should water coming out of the outboard be hot?

Answer: The water will be warm but not super hot. When it’s warm you know the water is pulling heat out of the engine to keep it cool as it should.

Bottom Line

We’ve just shown you all the solutions for your Yamaha outboard not pumping water. We are hopeful that you can fix this problem by yourself.

Don’t hesitate to share your experience while restoring your water pump. Encouragement helps us to grow.

So, let’s hope that nothing goes wrong and best of luck.

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