Five Ways to Make Your Outboard Engine Perform Better


If you’re a boater who was born before 1980, your first outboard engine memories probably resemble this: An adult male relative (your father, most likely) is bent over the the family skiff’s smoke-belching, cantankerous two-stroke engine with a can of starting fluid in one hand and a hammer in the other. More simply put, you remember outboard engines of those days as perhaps the most unreliable way to push a boat through the water since, well, forever.

Luckily for all of us, modern two- and four-stroke outboards are super reliable, requiring a minimum of tinkering and massaging to run well. But that doesn’t mean you can “set it and forget it.” like a rotisserie oven you may have seen advertised on late-night television. In fact, these uber-reliable outboards are good enough to have made us complacent, which means they often don’t get the attention they need to run their best. Here are five things you can do to make your outboard purr:

1. Focus on Fuel

Ethanol-spiked fuel is the modern outboard engine’s arch nemesis. The “too long; didn’t read” version of the ethanol follies is that ethanol, which is blended into billions of gallons of gasoline each year, attracts water. Even the smallest amount of water in your fuel can affect performance, which means you need to be on top of maintaining that fuel from the moment you pump it into your tank.

The first thing you want to do when you fuel up is add a quality fuel stabilizer; this will keep the ethanol in the fuel from over-saturating before it separates into a gloppy mess. Keep in mind that this separation—called phase separation—can happen is as little as a couple of weeks. Stabilizers also contain enhancers that improve fuel combustion, which improves performance. Give your fuel some love today, right when you put it in the tank, and your engine will return that affection with solid, reliable performance.

2. Focus on Filters

Did you know that a Yamaha F300 has not one, not two, but as many as nine separate fuel filters onboard? Well, it does, but no matter whether you have one fuel filter or nine, keeping filters fresh and clean is vital to getting top performance out of your engine. Modern outboard engines rely on clean, sediment- and water-free fuel to achieve top performance. Ensuring yours have been serviced properly is an easy way to get top-notch performance out of your outboard.

The unfortunate thing about some of these filters is that they either require proprietary tools to be removed, or the removal procedure itself is sufficiently complicated to require a pro to do the job. It’s no excuse not to keep up with the filter maintenance intervals recommended by your manufacturer, though — and if you’re religious about dealing with the owner-servicable filters you’ll save yourself a lot of trouble in the long run. If it’s been longer than you can remember since your filters were changed, your engine performance is likely suffering as a result.

Check your air filter, too. If you’re running an outboard with a dirty air filter, the difference in performance with a new, clean one will astound you. Don’t know if yours has one, or not? Enlist your outboard shop pro for help. Finally, always change your oil filter when you change your engine oil.

3. Focus on Fluids

Just like a marathon runner, outboard engines need lots of fresh fluids to run their best. The obvious life-giving fluid for four-stroke outboards is internal engine oil, while for two-stroke outboards it’s two-stroke oil mixed with the gas.

Oh, and you’ve changed your lower-unit gear oil recently, right? Both two- and four-stroke outboard engines carry lower-unit oil to cool and lubricate the gears at the bottom end of the outboard. Fresh, new fluid keeps these gears, and the engine that spins them, operating at peak performance. Make sure you change this oil with the manufacturer-recommended lube at least once a year, preferably at the end of the season, before layup.

Four-stroke outboard engines require clean engine oil to run smoothly and efficiently. As with the other items in this list, if you can’t remember the last time yours was changed (along with the oil filter), now is the time. An engine with fresh oil runs cooler and more efficiently. Most DIY boaters with average mechanical knowledge can change their own oil , but if you’re unsure about properly performing this task, have your local outboard shop do it for you.

Two-stroke outboards don’t have internal engine oil, but instead use two-stroke oil that is blended into the fuel to lubricate the cylinder walls and other engine internals. This is one of those areas where it doesn’t pay to cheap out; always use the manufacturer’s recommended two-stroke oil, even if it’s more expensive than the cheapest jug on your marine shop’s shelves.

4. Check Your Propeller

When was the last time you took a good look at your outboard’s propeller? Can’t remember? Well, it’s time to have a look. Even the smallest ding, dent, or scratch can wreak havoc with overall outboard performance, especially when it comes to speed, acceleration, and fuel efficiency.

You’ll want to look for chips and dings on the propeller’s outside edges, bent or distorted propeller blades, or corrosion and pitting. Aluminum props are especially prone to the latter. Some propellers can be tuned and refurbished at a reputable propeller shop, while some may need outright replacement. If you’re in doubt, take the offending prop to your local outboard shop for an assessment. Once you’re running with a new or refurbished propeller, you’ll feel your overall performance and efficiency surge.

5. Know Your Service Mechanic

Like it or not, all of this performance, efficiency, and reliability come at the expense of complexity, and that means there are just some things you may not be able to do on your own when it comes to scheduled outboard maintenance. The best thing you can do, if you own an outboard engine of any sort, is to find a mechanic you trust, and who comes recommended by boating friends. Almost every modern outboard out there has a maintenance schedule that really isn’t optional. Well, it is, but you won’t like your options if you don’t follow it. One of the best things you can do to ensure your engine is running at its best is to get up-to-date on your scheduled services today.

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