Ferlin Motor

Repowering Older Yamaha Outboard Motors

Just because your Yamaha outboard motor has aged doesn’t mean it’s not capable of running like new. Engines can be expensive, so it’s always a good idea to consider trying to repower an old one than shelling out money for a new one that you may not need just yet. If you’re not sure where to begin, we’ve got you covered. ferlinmotor Outboard Marine has created this guide to help you get started on repowering your older Yamaha outboard motor. There are some key components you’ll want to address. Keep reading for more information.

If you need assistance with repairs, give us a call or stop by and see us. We’d also be glad to help you pick out the perfect Yamaha outboard motor if it’s time to invest in a new one. We’re located in Miami and Key Largo, FL.

Fuel System

Over time, ethanol and heat can take their toll on the rubber and plastic components in your Yamaha outboard’s fuel system. This can lead to dangerous fuel leaks or even cause air to get into the system, which will make it hard to start and keep running. More often than not, fuel lines will become hard and brittle as they deteriorate.

Other culprits that can make an outboard hard to start are aged fuel pump diaphragms and check valves. The good news is that it’s not too difficult to replace the fuel lines on an outboard hose that’s made of modern materials that are built to withstand ethanol. You’ll want to invest in fuel lines that are specifically designed for marine use and that can handle ethanol. There are kits you can buy to rebuild pulse-type fuel pumps that come with new, ethanol-tolerant diaphragms and check valves.



The propeller is one of the most vital components of your Yamaha outboard. Take some time to inspect it to see what state it’s in. If it’s in especially bad shape, you’re going to need to repair or replace it to enhance the engine’s performance. Examine the blades to see if they’re bent or if the cupping is worn.

Some issues are beyond repair, but there is the possibility of fixing the blade alignment. With that said, if your propeller is extremely old, you may want to get a new one regardless of its condition. After all, propeller design has improved a lot over the years. An upgrade to a new model could have a positive impact on performance.


Water Pump

When repowering an old Yamaha outboard motor, don’t forget about the water pump. It might not have touched fuel, but the rubber impeller will become dry and stiff as time goes on. This is especially true if you haven’t used the motor very often. On the other hand, if it’s been used quite a bit, the impeller vanes could be worn. If this is the case, it’s possible that the water pump is not delivering full pressure to the cooling system.

When the pump eventually fails, you may not notice it until your motor overheats. You can prevent all of this by simply replacing the old impeller. Inspect the pump housing while you’re at it, which can also need replacing if it’s been scored by sand. The last step in this section is to inspect the water intake ports on the lower unit for debris blockage. If you find any, you can clear it with a stiff wire.


Spark Plugs & Wires

If you’ve owned a two-stroke Yamaha outboard for a while now, you probably know how important it is to regularly replace the spark plugs with a new set. The wires are crucial, too. Heat and ozone can cause your spark plug wires to age, which means you’ll need to replace them sooner or later.

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