Removing an Outboard VRO (Variable Ration Oiler) should you do it or not?

There are some positive and negatives to deleting a VRO on an modern outboard motor.  We will discuss them here.  In the end it will be your decision to make.  It's not a simple decision to make, and that decision is something we encourage you to learn a thing or two about before you go messing with a VRO system.

Two stroke motors pretty much since it's beginning of its birth used a combination of gas and oil mixed together.  Originally as you can imagine the gas and oil was mixed together in the tank.  You simply mixed according to the manufacturers specifications.  Depending it could be 25:1, 50:1 or even 100:1.  You use a measuring cup and put however much oil to a gallon of gas.

What does that mean?  Well for every 1 part of gas it represents the oil-to-gas ratio. It indicates the amount of two-stroke oil that should be mixed with a certain volume of gasoline for proper engine lubrication. The chart below is a typically mix chart.  example:

• A 25:1 ratio means you would mix 25 parts of gasoline with 1 part of two-stroke oil.
• A 50:1 ratio means you would mix 50 parts of gasoline with 1 part of two-stroke oil. 

  

Two-stroke engines may have different recommended ratios, so it's important to check the manufacturer's guidelines for your specific motor. Using the correct ratio is crucial for optimal engine performance and longevity. If you're unsure, consult your engine's manual or contact the manufacturer for guidance. 

To qoute a veteran technician, "Vro stands for variable ratio oiling. It varies from 150:1 to 50:1. And as long as it is serviced and has clean supply of oil it works good. Most failures were from water in oil tank or clogged filter in oil tank."

Look for the TC-W3 emblem.  It is the most widely used recommended oil for outboard engines. It's important to choose the right oil, for instance oils for weed eaters or chainsaws don't contain TC-W3 and using this oil will destroy your outboard engine.

The Variable Ratio Oiler (VRO) is a system used in some outboard motors to automatically mix the correct oil-to-gas ratio for the two-stroke engine. In two-stroke engines, a mixture of oil and gasoline is used for lubrication, and getting the right ratio is essential for proper engine lubrication.  In a 4 stroke the oil is in the engines pan, just like a modern car.  But, that's not the case for a 2 stroke.

The VRO system consists of a pump that varies the oil delivery based on the engine's needs. Typically measures engine speed, throttle position, and other factors to adjust the oil-to-gas ratio accordingly. This system eliminates the need for manually mixing oil and gas, as it automatically provides the correct mixture for optimal engine performance and lubrication.

It's worth noting that while VRO systems were used in the past, many modern outboard motors have shifted to direct fuel injection systems or EFI (electronic fuel injection) , which offer more precise control over the fuel mixture and improve fuel efficiency. 

The decision to delete a Variable Ratio Oiler (VRO) system in an outboard motor is often related to personal preferences, maintenance considerations, or troubleshooting issues. Here are a few reasons why some people choose to delete or bypass the VRO system:

1. Prefer Premixing: Some boaters prefer to manually mix the oil and gas themselves rather than relying on the VRO system. This gives them more control over the oil-to-gas ratio and allows them to use specific types of oil that might not be compatible with the VRO system. vs. A seperate tank and lines.

2. Maintenance Concerns: The VRO system involves additional components, such as pumps and sensors, that could be prone to wear and failure. Some boaters choose to bypass the VRO system to simplify maintenance and reduce the risk of potential issues.  Such as engine failure.

3. Reliability: There have been instances of VRO system failures in the past, leading to engine problems. To avoid such issues, some boaters choose to delete the VRO system and rely on manual premixing for what they consider a more reliable solution.

4. Troubleshooting: If a boater is experiencing problems with their outboard motor and suspects issues with the VRO system, they might choose to delete or bypass it temporarily as a troubleshooting measure. This can help determine whether the VRO system is the source of the problem.

5. Personal Preferences: Some boaters simply have personal preferences or specific reasons for wanting to eliminate the VRO system. It could be based on previous experiences, recommendations from others, or a desire for more hands-on control over the fuel mixture.

There are several advantages with a Variable Ratio Oiler (VRO) system and that is why these systems are designed and implemented by manufacturers. Here are some of the pros of using a VRO system versus deleting the system altogether.

1. Convenience: One of the primary advantages is the convenience of not having to manually mix oil and gas. The VRO system automatically adjusts the oil-to-gas ratio based on engine speed, throttle position, and other factors. This simplifies the fueling process for boat owners.

2. Optimal Lubrication: The VRO system is designed to provide the correct oil-to-gas ratio for optimal lubrication of the two-stroke engine. This helps ensure proper engine performance, reduces wear and tear, and extends the life of the motor.

3. Reduced Emissions: By automatically adjusting the fuel mixture, the VRO system can contribute to more efficient combustion, potentially reducing emissions. This is particularly relevant in today's context where environmental considerations are important.

4. User-Friendly Operation: For boaters who are not familiar with or prefer not to manually mix oil and gas, the VRO system offers a user-friendly solution. It simplifies the fueling process, making it accessible to a wider range of users.

5. Less Chance of Mixture Errors: Since the VRO system automates the mixing process, there's less chance of human error in determining the correct oil-to-gas ratio. This can prevent potential engine damage that may result from using an incorrect mixture. Such as ring carbon build up cause the rings to not move in the piston.

6. Adaptability: The VRO system adjusts the oil delivery based on various engine parameters, making it adaptable to different operating conditions. This flexibility allows the engine to receive the right lubrication at all times.

7. Manufacturer Integration: VRO systems are often integrated into the design of outboard motors by manufacturers. This integration ensures that the system is calibrated and optimized for the specific engine model, providing consistent and reliable performance.

It's important for boat owners to follow the manufacturer's recommendations and guidelines regarding the use and maintenance of the VRO system to maximize its benefits and ensure proper engine operation.

Johnson and Evinrude, Mercury and others have produced a variety of outboard motors with different pumps and fuel delivery systems. The reliability of a pump can depend on factors such as the old is it?  What version of the pump is it?  Is it version 1? Or, is it the second version of that pump (what model is it) and how it was maintained.

Here are a few notable pump systems used in Johnson and Evinrude outboard motors:

1. VRO (Variable Ratio Oiler): The VRO system, which automatically mixes oil with fuel to provide the correct oil-to-gas ratio, was used in many Johnson and Evinrude outboards. While some users have reported issues with the VRO system, many have found it to be a very reliable system when properly maintained. Regular maintenance and adherence to recommended oil and fuel types are crucial for its optimal performance.

2. Fuel Pump: The fuel pump in outboard motors plays a critical role in delivering the right amount of fuel to the engine. Johnson and Evinrude outboards have used various fuel pump designs over the years. Generally, routine maintenance and periodic inspection of the fuel system can contribute to reliability.  In the case of a carburetor failure say in a 2 cylinder engine if the bottom carb gets clogged up then that cylinders may fail from lack of lubrication.  So its good to know that any system is prone to failure..

3. Electric Fuel Pump: In some models, particularly those with electronic fuel injection (EFI) systems, electric fuel pumps are used. These pumps are designed to provide precise fuel delivery, enhancing performance and efficiency.

4. Water Pump: While not directly related to fuel delivery, the water pump in an outboard motor is essential for cooling the engine. Regular replacement of the water pump impeller and other components is crucial for preventing overheating and ensuring reliable engine operation.

The reliability of any pump or system in an outboard depends on factors such as proper maintenance, usage conditions, and adherence to manufacturer guidelines. Additionally, the availability of parts and support for older models may influence the overall reliability of pumps in Johnson and Evinrude, Mercury, Yamaha Suzuki hopefully you get the idea. Boat owners should consult their engine's manual, follow recommended maintenance schedules, and address any issues promptly to ensure the reliability of the fuel delivery system.

Typically the pumps has five lines on the pump, a gas input, an oil input, a pulse from the engine, an output which is mixed fuel to the carburetor, a primer circuit (choke) output to the carburetor. 

The Variable Ratio Oiler (VRO) system is a mechanical device designed to automatically mix oil and gasoline in the correct ratio for two-stroke outboard motors. The VRO system operates based on the engine's needs and adjusts the oil-to-gas ratio accordingly. While specific designs may vary between manufacturers and models, the basic operation of a VRO system typically involves the following components and steps:

1. Oil Reservoir: The VRO system includes an oil reservoir where two-stroke oil is stored. This reservoir is usually mounted on the outboard motor.

2. Fuel Pump: The system incorporates a fuel pump responsible for delivering gasoline to the engine. This pump is often driven by a mechanical connection to the engine's crankshaft.

3. Diaphragm Mechanism: A key component of the VRO system is a diaphragm mechanism. This diaphragm is typically connected to the throttle linkage and responds to changes in engine speed and throttle position.

4. Pulse Signal: As the engine operates, the diaphragm receives pulse signals that correspond to engine speed and throttle opening. These signals are generated by the engine's operation and are used to determine the amount of oil required for proper lubrication.

5. Oil Metering Valve: The VRO system features an oil metering valve controlled by the diaphragm. The valve regulates the flow of oil from the reservoir to the fuel pump based on the received pulse signals.

6. Mixture Delivered to Carburetors: The oil metering valve, in coordination with the diaphragm and pulse signals, adjusts the oil flow rate. The correct mixture of oil and gasoline is then delivered to the carburetors or fuel injectors.

7. Engine Lubrication: The oil-gasoline mixture is introduced into the combustion chamber, where it provides lubrication for the engine components, such as pistons and cylinder walls, during the combustion process.

The key idea behind the VRO system is to automate the oil-to-gas ratio adjustment, ensuring that the engine receives the appropriate lubrication under varying operating conditions. Regular maintenance, including checking and cleaning components, is important to ensure the proper functioning of the VRO system and prevent issues that could affect engine performance.

To Test a VRO on a Johnson Evinrude the service manual lists two static tests on the VRO which can be done. This requires removal of the pump from the engine and you'll need a pressure tester and vacuum tester.  These tests will check the integrity of the units air motor diaphragm and rectifier valves.

Install a pressure tester to the fuel inlet and pressurize to 6 to 8 psi. This actually tests the integrity of the oil piston seal which usually causes the VRO to over-oil rather than dilute the oil with fuel. A complete failure of that seal could however cause fuel to get into the oil, but that is a pretty rare thing to happen.  You can also do a running test which can be performed on the unit to determine its oil consumption.   

Having oil injection is a notable convenience, however the choice to disable it is yours.

To disable first remove the oil supply line from the lower motor cover (under the fuel line plug in) and securely cap the fitting so dirt, water or other contaminants can't get in and later gum up the works. Next, find the 3 or 4 wire harness coming from the VRO and disconnect the amphenol connector (round, black rubber about 3/4" in diameter, about 2" long). This disables the "no oil" alarm and averts false warnings. Find the 2 wires from the oil tank and trace them to where the connect on the motor and disconnect them and pull the wires back to the tank, tape up any connections remaining under the hood of the outboard. Remember to pre-mix your fuel at a 50:1 ratio and that's it. 

It's important to note that modifying the lubrication system of an outboard motor should be done carefully, and it's crucial to follow manufacturer guidelines and consult with experts if needed. Deleting the VRO system may impact warranty coverage, so it's advisable to consider these factors before making any modifications.

The EPA had a big role in this.  Guidelines from the EPA caused the major manufacturers to design systems to improve the performance and emission standards of the time of manufacture.  If these engines did not meet the standards then they were prevented from being sold.   Engineers designed the VRO system to better the performance of these engines.  

We recommend keeping them in place with OEM replacements.  Its important to keep the warning horn in proper working order.  These older systems did not have modern smart meters for the driver to monitor the engines conditions.