Replacing Vro Pumps: Evinrude Fuel Pump Switch

Replacing a VRO pump with a fuel pump on an Evinrude engine is a common procedure, as the VRO pump is known to be unreliable. There are a few ways to go about this, depending on the model of the engine and personal preference. One way is to install a standard diaphragm fuel pump, which can be purchased from various online retailers and marine stores. This type of pump is usually mounted on the engine block and requires the removal of the pulse limiter and the installation of a plug in its place. Another way is to use the VRO pump as a fuel pump by blocking off the oil side. This method is considered more reliable, as the VRO pump was designed to work with the engine and has been used on commercial and South American engines. When performing this replacement, it is important to acquire the correct fuel pump for the specific engine model, as well as to carefully follow the installation instructions and ensure all connections are secure to avoid fuel leaks.

Get the right replacement parts

The first step to replacing your VRO pump with a fuel pump is to get the right replacement parts. You can buy these on eBay or through a website like MasterTech Marine, which can help you select the correct fuel pump for your engine.

For example, if you have a 1996 Evinrude 50/35 jet, you can use Evinrude 438559 as a replacement. This pump has three barbs: one for fuel input, one for fuel output, and a pulse line to drive the pump. There is also a block mount model that can be installed on VRO motors.

If you have a 2000 50 hp Johnson, you can use pump part # 438556, or Sierra 18-7352. This pump mounts on the port side of the crankcase and has a gasket that will seal the pulse of air that comes from the pulse hole in the block to operate the pump.

For Johnson/Evinrude engines, if you want to convert from a VRO to a standard pulse-type pump, simply go back in time in the parts catalog and use a pump for the same horsepower engine before they switched to the VRO. For example, if you have a 70 horsepower engine, use the pulser pump from a 1984 and older 70 horsepower engine. The pump you need is part number 0385784.

If you are unsure about which replacement pump to get, it is best to consult a mechanic or a website that specializes in marine parts to ensure you get the correct part for your specific engine.

In addition to the fuel pump, you may also need to purchase new screws to secure the fuel pump in place, such as OMC part # 0314417. It is also a good idea to change the fuel filter if it is due for a replacement. You can opt for a street application filter like the Edelbrock filter, which is small and has a replaceable sintered brass filtering element.

Finally, you will need fuel lines to connect the new pump. You can reuse your old fuel lines if they are in good condition, or you can purchase new ones. Standard 3/8" ID fuel hose is available at most auto parts stores. If you are reusing your old lines, make sure to check for any cracks or damage that could cause leaks.

Remove the old fuel line and components

Removing the Old Fuel Line and Components

Let's begin with the VRO oil pump side. Disconnect the hoses from the oil pump's fuel manifold. There are three hoses in total; carefully detach the hose connecting the manifold to the oil pump on the manifold side. The fuel manifold should now be completely separated from the VRO oil pump.

There will be three hoses connected to the oil pump. One of them is the hose you just removed from the manifold. The other two are a hose that goes to the fuel filter and another that snakes beneath the starter to the engine block. Disconnect these two hoses from the manifold. The manifold should now be disconnected from all hoses. There will be one electrical connection remaining that attaches the VRO oil pump to the engine. Disconnect the low/no oil sensor. Tape up the loose end and tuck it out of the way.

I wanted to replace all of my fuel lines, so I disconnected the hoses from the manifold. Unfortunately, one of the barbs on the plastic manifold broke off during this process. I discovered that OMC/BRP had discontinued this part due to its brittleness and tendency to break. You can still buy them from old stock for around $35, but the replacement part is all brass and costs about $80.

Broken Fuel Manifold and Replacement Brass Fuel Manifold

I ended up constructing a new manifold myself using parts from Amazon. I purchased the correct size hose nipples and junctions, all in brass. To simplify the process, I kept all the male and female fittings the same size (1/4″ npt). The main fuel line nipple to the manifold is a 3/8″ barb, while the three nipples feeding the carburetor are 3/16″ barb fittings. The overall cost was around $35, far less than the $85 for the OEM part!

The last thing to remember is to use a sealer that is resistant to gasoline. Teflon tape is generally not recommended for fuel lines as small fragments can break off and clog ports and jets in the carburetors.

Plugging the Impulse Line

There will be one remaining hose. You have two options here. The first option is to install a stainless steel screw into the impulse line and tighten it with a hose clamp. Alternatively, you can remove the hose and the barb fitting from the block, but you'll need to find the right size bolt, and you'll probably have to take the starter off to access that port. I elected to plug the hose for now, and I'll likely eliminate the hose altogether and plug the impulse port directly when I service the starter in the future. If you go this route, be sure to install a gasket or thread sealer on the bolt.

Plug the impulse line

To replace a VRO pump with a conventional fuel pump in an Evinrude outboard engine, you will need to plug the impulse line. This is a crucial step to ensure the proper functioning of the fuel pump and engine. Here is a detailed guide on how to plug the impulse line:

Locate the Impulse Line: The first step is to identify the impulse line, which is responsible for delivering pressure and vacuum signals to the fuel pump. This line is usually connected to the lower end of the block near the starter. It is important to note that the location may vary depending on the specific Evinrude model you are working on.

Disconnect the Impulse Line: Before plugging the impulse line, you will need to disconnect it from the fuel pump or the block. Using appropriate tools, carefully detach the line from its connection point. Make sure to note the routing of the line to ensure proper reinstallation if needed.

Secure the Plug: Once the plug is in place, make sure it is secure and will not come loose during engine operation. You can do this by applying a thread locker or sealant to the plug's threads before installation. Additionally, you can use a locking washer or thread-locking compound to ensure the plug remains in place.

Test the System: After plugging the impulse line, it is important to test the fuel pump and engine to ensure proper functioning. Start the engine and observe for any leaks or unusual behaviour. Check the fuel pump's pressure and vacuum readings to ensure they are within the normal range. If you notice any issues, re-inspect your work and ensure that the plug is secure and properly sealed.

By following these steps, you can effectively plug the impulse line when replacing a VRO pump with a conventional fuel pump in an Evinrude outboard engine. Remember to work carefully and refer to specific Evinrude service manuals or seek professional assistance if needed.

Install the new fuel pump

Now it’s time to install the fuel pump. On older Johnson and Evinrude models (for example, a 40hp engine), you’ll find the port and mounts on the starboard side of the engine. It will be between the starter and the main battery connector (positive). You may have to do a little research for your model, but most outboards with VRO oil pumps have the second option for a fuel pump only.

You’ll want to remove the bolt from the mounting point. It is recommended to clean the area with a small steel brush prior to proceeding with the install. Before installing the new fuel pump, you may want to set the gasket in place and push the screws through. This will make mounting the fuel pump easier. Place the fuel pump in place, lining up the screws with the mounts and tighten the screws until the fuel pump is firmly in place.

Next, you’ll be connecting the fuel lines. You can reuse your original hoses, but it is recommended to replace them, especially if the engine is over 30 years old. From the manifold to the carbs and primer (as well as back from the primer) you can use Polyurethane racing fuel lines. From the fuel inlet to the filter, pump and finally the manifold, you can use standard 3/8″ ID fuel hose available at most auto parts stores.

Assuming you are reusing your old fuel lines, you’ll need to reposition the filter so that the fuel goes through the filter before hitting the pump. With this particular pump, it is ok to do that as all there is underneath the pump is a screen to pre-filter the gas before it hits the pump. Other pumps may be different, so do your homework for the particular pump you will be using if you need to reposition the cover.

In the case of reusing the old plastic manifold, flip it upside down. In the old configuration, the VRO oil pump fed the manifold from the top, but in this case, you will be feeding it from the bottom.

After getting everything together, it is recommended to pressure test the entire system with the primer bulb. Running the engine on a hose muffler for a few minutes to pressurize the system while operating and checking for leaks is a good idea to ensure that there are no leaks under operating conditions.

Replace or reuse fuel lines

When replacing the VRO pump with a conventional fuel pump, you may need to replace the fuel lines. This is because the VRO pump has a different number of nipples/barbs, which connect to the fuel lines. The VRO pump has three nipples, while a conventional fuel pump has two. Therefore, you will need to either:

• Reuse the existing fuel lines and adapt them to fit the new fuel pump. This may involve cutting and joining the fuel lines, or using additional connectors.
• Replace the fuel lines with new ones that are designed to fit the new fuel pump.

It is important to note that some VRO pumps were used as both a fuel pump and an oil pump, so if you are removing the VRO pump and switching to a conventional fuel pump, you will need to ensure that you have a separate oil pump or are mixing the oil and gas manually.

When replacing or reusing fuel lines, it is recommended to use marine-grade fuel lines and connectors. Fuel lines come in different sizes, so you will need to check the size of your engine's fuel line connections to ensure you purchase the correct size.

Additionally, if you are replacing the fuel lines, it is a good opportunity to inspect and replace any other lines or connectors that may be worn or damaged. This includes the "under-cover" lines, which are typically located near the engine and fuel tank.

Finally, when working with fuel lines, it is important to exercise caution and refer to the appropriate safety guidelines, as fuel can be flammable and hazardous to your health.

Frequently asked questions