Why Remove the VRO Oil Pump?
Running an older outboard can present some challenges. One of them is the constant worry of having the VRO oil pump go out on you. Many boaters elect to bypass a Johnson or Evinrude oil pump. There is a ton of information in the Internet on how to do this. The problem with this is that you still have a VRO oil pump acting as a fuel pump. In my opinion, this is a failure point waiting to happen. Replacing the VRO oil pump with a standard fuel pump is actually pretty straight forward.
Replacing the VRO Oil Pump
Get the Right Parts to replace the oil pump
First, get a replacement fuel pump. You can buy these on ebay, There is also a good website that can help you select the correct fuel pump for your engine. MasterTech Marine can guide you in selecting the right fuel pump for you outboard. They also have a good technical section that can provide some tips on removing the VRO oil pump and replacing it with a fuel pump.
In the case of my engine, I had to order two screws that would be long enough to secure the fuel pump in place. You might get lucky and get the screws with the fuel pump you buy. But make sure you have these on hand so you will have everything you need before starting. I ordered the original OEM screws for my 40hp Johnson, OMC part # 0314417.This might also be a good time to change the fuel filter if it’s due for a change.
I opted to go with a Edelbrock filter. It’s meant for street applications on cars but is rated up to 300hp. The key things I like about this fuel filter is that it is small, which helps with space management under the cowling, and it has a replaceable sintered brass filtering element. The element can be cleaned or replaced as needed. I’ll revert back to an OEM style filter should I have any issues with this one but I think this filter will work out fine.
Removing the Old Fuel Line and Components
Let’s start at the VRO oil pump side. You will be disconnecting some hoses from the oil pump. There are three hoses that come off of the pump fuel manifold. You can leave those hoses connected as you will be re-using that manifold. carefully disconnect the hose coming from the oil pump to the manifold (on the manifold side). The fuel manifold should now be completely free of the VRO oil pump.
There should be three hoses now connected to the oil pump. One of these is the hose you just took off of the manifold. The other two are a hose that goes to the fuel filter and a hose that snakes underneath the starter to the engine block. Disconnect these two hose from the manifold. The manifold should now be disconnected from all the hoses. There will be one electrical connection that still attaches the VRO oil pump to the engine. That is the low/no oil sensor. You can disconnect that. Tape up the other end and tuck it so that it is not in the way of anything.
A Broken Manifold
I wanted to replace all of my fuel lines when doing this so had to disconnect the hoses from the manifold. Unfortunately one of the barbs on the plastic manifold broke off when removing the hose. I did a some research and found that OMC/BRP had discontinued that part. Probably because they are brittle and have a tendency to break. You can still buy them from old stock and they run about $35. The replacement part is all brass and runs about $80.
I ended up constructing one myself. Finding the parts to do this was relatively easy (Amazon). I bought the correct size hose nipples, and junctions, all in brass. To make things easier, I kept all of the male and female fittings to the same size (1/4″ npt). The main fuel line nipple to the manifold is a 3/8″barb and the three nipples feeding the carburetor are 3/16″ barb fittings. I can send you a complete list if you want to assemble one yourself. 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. The reason is that small fragments of Teflon may break off and clog ports and jets on the carburetors.
Plugging the Impulse Line
There will be one hose left behind. You have two options here. The first option is what I did, install a stainless screw into the impulse line (see Picture) and tighten it with a hose clamp. Alternatively, you can remove the hose and the barb fitting from the block. You’ll have to find the right size bolt for that, i have found references that call for 1/8″ SS or brass pipe plug. Unfortunately, you will probably have to take the starter off to access that port. I elected to just plug the hose for now. In the future, whenever I service the starter, I will probably eliminate the hose altogether and plug the impulse port directly. If you do go this route, make sure to install a gasket or thread sealer on the bolt.
Installing the new Fuel Pump
Now it’s time to install the fuel pump. On the older Johnson and Evinrude models (mine is 40hp), 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. There should be a small bolt (sealing the impulse port) and two mounts on either side of it (see picture).
You’ll want to remove the bolt from the mounting point. I cleaned the area off 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.
Replace or Reuse Fuel Lines?
Next you’ll be connecting the fuel lines. You can reuse your original hoses, I opted to replace all of mine since the engine is over 30 years old. From the manifold to the carbs and primer (as well as back from the primer) I used Polyurethane racing fuel lines. From the fuel inlet to the filter, pump and finally the manifold, I used standard 3/8″ id fuel hose available at most auto parts store.
I did this predominantly because of cost savings. You can buy OEM fuel line buy they are ridiculously expensive. There is also a durability factor, unlike rubber compounds, Polyurethane line does not deteriorate. The original fuel lines on this 1988 Johnson 40HP outboard has some real odd ball sizes. I used replacement lines that were close and provided a snug fit then secured them with either a tie wrap or hose clamp. Here are the size hoses and clamps I used to replace all of the original fuel lines
- Main Fuel Line (fuel filter, pump and manifold 3/8 ID EDPM Fuel Line – SS Hose Clamps
- Primer to Carbs 3/16″ ID – Tie Wrap
- Manifold to Carbs and Primer 3/32″ ID – Tie Wrap
My Concern with Polyurethane Fuel Line
My one concern was the heat resistance of the Polyurethane line. I did a bit of research and found that the melting point of the polyurethane fuel line 370° F. This is well above the operating temperature of the engine. There is only one spot where the poly fuel lines can contact the block. That is between the primer and the fuel manifold as well as the carbs. So to be safe, I used fiberglass tubing heat shield around those sections of hose that could come in contact with the engine block.
Install the Fuel Lines
Assuming you are reusing your old fuel lines, you’ll need to re-position the filter so that the fuel goes through the filter before hitting the pump. I moved the pump fuel inlet cover to accommodate the fuel line routing I used. 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 re position the cover.
In my case, I installed a short section of 3/8″ ID hose to the filter, a longer section of the same hose to the pump and then ran an even longer section of the 3/8 ID hose to the manifold. If you are reusing the old plastic manifold, flip it upside down. In the old configuration, the VRO oil pump fed the manifold from the top, in this case you will be feeding it from the bottom.
I used SS hose clamps on all of these particular fittings. After getting everything together, I pressure tested the entire system with the primer bulb. I wanted to make sure there were no leaks that were apparent. Running the engine on a hose muffler for a few minutes to pressurize the system while operating and check for leaks is a good idea to insure that there are no leaks under operating conditions