3 Yamaha 250 Outboard Problems You Should Know (Explained)

The Yamaha F250 has been labeled one of the best outboard engines ever made.

The reasons given include their reliability, top-end power efficiency, low noise levels, and Yamaha spare parts’ availability from dealerships and local service centers.

However, while the Yamaha 250 outboard has many fans, there are a few problems to look out for:

A Brief History Of The Yamaha 250 Outboard Engine

The Yamaha Motor Company has been developing marine outboard motors since 1958.

Their first model was a  250cc 2-stroke engine prototype which was large and clumsy. It was so heavy that an engine mount broke during a test run, and the engine dropped into the water!

Because this prototype engine was so cumbersome, it never actually made it into production.

But by July 1960, Yamaha released its first outboard motor onto the market, the P-7. They had abandoned the 250cc model in favor of an air-cooled, 2-stroke, 123cc (about 7hp) model, which was lighter and easier to manage.

In 1970, Yamaha entered the US market with their commercial range of Enduro engines which paved the way for the company to enter the leisure market in 1981. By 1983, Yamaha offered a full range of 2-stroke outboard engines, from 40 to 220hp.

The birth of larger horsepower 4-stroke engines came much later. Yamaha only broke the 4-stroke 100hp barrier in 1998 when they started to introduce bigger 4-stroke outboard engines.

While no one believed that the outboard engine would get much bigger than this, just 3 years later, in April 2001, Yamaha launched their F225, a V6 225hp outboard motor which was a resounding success.

This success was based on the fact the F225 was as compact and as light as a 2-stroke engine of the same horsepower. This, combined with the positives of a 4-stroke engine, namely the fuel efficiency, lower exhaust emissions, and a quieter engine, made it an extremely popular engine.

Due to the success of the F225, Yamaha went on to produce the F250 in 2004. Since its introduction, the F250 has consistently been ranked within the top 5 of all brands of 250hp outboard engines.

The Yamaha F250 Specifications:

Engine Type V6
Displacement 4.2L
Bore x Stroke 96 x 96mm (3.78 x 3.78in)
Prop Shaft Horsepower 250hp at 5500 rpm
Full Throttle RPM Range 5000 ~ 6000 rpm
Alternator Output at W.O.T. 50 – 70 Amp
Compression Ratio 10.3:1
Fuel Induction System EFI
Weight † 250 kg (551 lbs) / 254 kg (562 lbs) / 265 kg (588 lbs)
Recommended Fuel Octane 87
Recommended Engine Oil Yamalube® 4M (See owner’s manual)
Recommended Fuel Filtration Yamaha 10-Micron Fuel / Water Separating Filter (external)

[Table courtesy of yamahaoutboards.com]

3 Yamaha 250 Outboard Problems You Should Know

While the Yamaha F250 has its ardent supporters and has a reputation for being extremely reliable, the following are problems that you need to look out for:

1. Exhaust Corrosion Issues

According to the various boating forums, the Yamaha 250 had some exhaust corrosion issues in older models until 2008. Yamaha was aware of the problem but did not admit it was a manufacturer’s defect apart from offering repair kits for sale.

While some people believe that using the engines in salt water and not flushing the engines properly after each use was the cause of the exhaust corrosion issue, this was not the case. The exhaust on this engine is dry, so using the engine in saltwater and flushing the engine has nothing to do with it.

The exhaust corrosion issue has more to do with the protective coating that was used being sub-standard. The corrosive nature of the exhaust emissions erodes the said coating and causes the area around the exhaust stack to corrode or rust away.

The signs that tell you if a Yamaha 250 engine is suffering from this corrosion include large bubbles rising when the engine is idle and the lower unit is submerged. The overheating alarm goes off when idling but stops when you add some throttle.

However, the only way to know for sure is to physically remove the powerhead and examine the exhaust housing. An endoscopic inspection, also known as scoping, can give you a good indication, but the definitive diagnosis is based on a visual inspection once the powerhead has been removed.

2. Yamaha 250 Oil Pump Problems

The oil pump and the oil pump seals are known to give problems on the Yamaha 250.

If the oil pump seals have failed, you will usually notice a film of oil on the water surrounding your engine or on the ground underneath. A repair will require the removal of the powerhead from the lower casing, and then you should easily be able to replace the seals.

Other problems with the actual oil pump include the electric pump failing, faulty wiring causing the ‘low oil’ alarm to go off, the float switch in the oil reservoir not working, and something as simple as a blocked filter.

But, the good news is that as the electric oil pump and the related switches all have voltage going to them, troubleshooting is fairly simple. However, before tackling any job, read the manual first. It may save you many frustrating hours of labor.

Proper troubleshooting techniques combined with a good understanding of the system means that you can easily fix most oil pump problems.

3. Yamaha 250 Fuel System Issues

An outboard motor that doesn’t run smoothly fails to deliver maximum power (or get up on a plane), struggles to idle, or stalls regularly could be experiencing fuel pump problems. However, this could apply to any outboard engine, not just the Yamaha 250.

The modern outboard engine has a very complicated fuel system. The days of a gravity-fed fuel system, with a fuel line leading from the tank to a carburetor, are long gone.

Today’s fuel systems contain primary and secondary fuel filters, low-pressure and high-pressure fuel pumps, vapor separator tanks (VST) and VST filters, and a high-pressure fuel rail that delivers the fuel to the fuel injectors.

Many of these components need specialized tools to work on them, so it’s best left to your dealership or a qualified mechanic.

However, if you suspect you have a fuel system problem, there are a few things that you can troubleshoot before resorting to the experts:

  • Both the primary and secondary fuel filters should be checked regularly and replaced after every 100 hours.
  • If you suspect a fuel pump failure check the voltage and electrical connections for power before you rush out to buy a new pump. The problem may be a blown fuse that needs replacing. However, if it is a blown fuse, this is a symptom of another problem. After all, what has caused the fuse to blow?
  • Always read through the Owner’s Manual of your outboard engine and follow any maintenance instructions to the ‘T..’ The manual provides handy troubleshooting tips that you can easily follow.

General Pros and Cons For The Yamaha 250 Outboard

Overall, the Yamaha 250 outboard engine gets excellent reviews on the various boating and fishing forums.

Just like any outboard, there are certain pros and cons:

The Pros

Yamaha has been designing and manufacturing outboard engines since 1958. Their entry into the US leisure boat market in 1981 was preceded by a decade of supplying outboard engines for the commercial market.

The Yamaha outboards’ reliability, extensive network of dealerships, and commitment to excellent customer service have contributed to Yamaha being the number 1 selling outboard engine worldwide, with an estimated 40% of the market share.

If properly maintained, the Yamaha 250 outboard can last up to 3,000 – 4,000 hours, with some commercial or charter users reporting that they have had up to 7,000 hours of use. These engines like to run.

In fact, according to surveys carried out by boats.com, this engine won the award for ‘The Most Reliable Outboard’ in 2021.

“…the ubiquitous Yamaha F250 is the hands-down favourite of boaters across the nation. In fact, it’s become something of an icon, powering fishing boats, cruisers, and even large pontoons as well as everything in between. This 4.2-litre powerhead has been around for close to a decade and has proven itself with unbeatable reliability in countless situations on countless transoms.”

[Source: Best Outboards In 2021, boats.com]

The Cons

  • The earlier engines (pre-2008) have well-documented exhaust corrosion issues.
  • The Yamaha 250 outboard may have oil pump problems.
  • The Yamaha 250 outboard can have fuel system issues.

Final Thoughts

Whether you are looking to buy a new or secondhand Yamaha 250 outboard motor, you can be sure you’re getting a top-quality engine.

These engines combine innovative design features with advanced engine systems to produce unmatched top speeds despite the problems mentioned above.

Yamaha is consistently known for its reliability and is committed to producing cleaner engines as a bonus. All this while offering great motors at a competitive price.


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