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Be Aware - 5 Common Yamaha F115 4-Stroke Problems


The Yamaha F115 is a great 4-stroke outboard motor which constantly receiving high marks for reliability, longevity, and performance.

This is due to the outboard’s 1.8-liter displacement and DOHC/SOHC designs with four valves per cylinder, providing a lighter weight and extraordinary volumetric efficiency. This option is the perfect choice for a mid-sized craft, with lots of bang for your buck. Originally put on the market in 1999, the Yamaha F115 has received a number of upgrades since then, improving the basic design with modern features. This suits both water sports enthusiasts and anglers alike.

Like all outboard motors, Yamaha 115 4 stroke outboard problems are bound to occur through heavy usage and aging of components. Despite its high performance, regular maintenance and servicing are required to keep this outboard motor in the water and out of the shop.

In this post, we will take a look at five of the most common Yamaha 115 4-stroke problems, including:

  1. Faulty head gasket

  2. Bad fuel pump

  3. Clogged fuel injectors

  4. Clogged VST filter

  5. Trim and tilt switch issues

1. Faulty Head Gasket

Over the lifetime of your Yamaha F115, the head gasket will eventually wear down and fail, causing severe damage to your engine if not addressed.

For novice boaters, the head gasket serves as an important component in the performance and lifespan of your Yamaha F115. Head gaskets are made of a non-porous material located between the cylinder block and the cylinder head (where your spark plugs are screwed in). Its purpose is to seal these parts together to both withstand the compression from the engine while also enabling water to flow between the block and the head for temperature regulation.

Over time, the head gasket of your Yamaha F115 is regularly exposed to a number of elements that reduce its integrity, such as salt water, heat, fuel, and other substances. Once a head gasket fails, water and other contaminants will enter your engine. That leads to poor performance (ie. engine bogging down, excessive vibrations), engine damage, and eventually failure – plus a hefty repair bill.

When it comes to Yamaha 115 4 stroke problems, replacing the head gasket should be a priority every 4 years of service, or sooner if usage exceeds the average boater (50 hours per season, or 200 hours for 4 years). There are also a number of other signs to pay attention to that may indicate faulty head gasket:

  • Idle runs too slow/rough

  • Low pressure in the cylinders (use a compression test to find out)

  • Holes and debris in and around the head gasket

2. Bad Fuel Pump