How to Switch My Evinrude 90 HP VRO Fuel Pump S to a Regular Fuel Pump

by Will Charpentier
Replacing the VRO2 fuel pump means mixing oil with gasoline by hand.

Replacing the VRO2 fuel pump means mixing oil with gasoline by hand.

Evinrude outboard motors with the VRO2 system don't require you to mix oil with the fuel. Instead, the oil is metered, as required, into the fuel the 2-stroke engine burns; hence the name "variable ratio oil" system. You can replace the VRO2 fuel pump on your 90-horsepower Evinrude if you've grown weary of keeping track of its oil usage. While this means you will have to mix oil with the fuel, you won't run the risk that a faulty "Low Oil" warning buzzer will cost you a severely damaged engine.

Removing the VRO2 Fuel Pump

1. Position a shop rag beneath the fuel pump to catch any fuel that may leak from the lines. Remove the black negative battery lead from the battery. Examine the VRO fuel pump and find the fuel outlet line to the carburetor on top of the pump. Cut the plastic zip tie that holds it in place, using a razor knife, and push the fuel line from the nipple on the pump.

2. Compress the spring clamp on the pulse line, found at the center of the front of the pump. Slide the spring back onto the line that branches out to each of the three carburetors. Remove the line from the pump. Push the branch lines from the fittings on the side of the top, middle and lower carburetor.

3. Compress the clamp on the bottom line of the fuel pump -- the oil inlet line that leads from the tank by way of the prime bulb -- and push it backward on the fuel line. Push the line from the fitting on the pump.

4. Feel around on the bottom-rear of the pump and find the oil supply line. The same type of spring clamp as the one used on the fuel inlet line keeps the oil supply line in place. Move the clamp back onto the line and remove the line from the pump.

5. Trace the pump wiring back to the point where it connects with the engine wiring harness. Disconnect the connector from the harness. Pull the wire from the wire loom.

6. Locate the three pump-to-manifold bracket screws on the backside of the pump-mounting bracket. Support the pump as you remove these screws with a flathead screwdriver, and lift the pump from the engine.

Removing the Oil Reservoir

1. Feel around on the bottom-rear of the oil pump and find the oil supply line. The oil supply line is secured by the same type of spring clamp as the fuel inlet line. Again, move the clamp back onto the line and remove the line from the oil pump.

2. Remove the screws that hold the starboard-side lower engine cover -- the engine cover on the lower right side of the engine -- in place. Remove the wire for the three-pin wiring connector for the oil reservoir from the wire loom and disengage the it from the wiring harness.

3. Remove the screw holding the top of the oil reservoir in place on the engine's top bracket. Plug the hoses leading from the tank with a golf tee to prevent oil loss. Remove the screw securing the lower part of the reservoir to the powerhead and pull the reservoir away from the engine.

Installing the New Pump

1. Place a bead of thread locker on the threads of the screws that will hold the new pump in position.

2. Position the gasket or O-ring that accompanies the pump onto the powerhead. Position the new fuel pump on the fuel pump mounting bracket and thread the three pump-to-manifold screws through the bracket and into the pump. Tighten the screws to 30 inch-pounds using a torque driver.

3. Connect the fuel outlet hose to the nipple at the top of the pump and secure in place with a zip tie. Compress the clamp on the fuel inlet line and slide the end of the line over the fitting on the bottom of the pump. Slide the clamp over the fitting to hold the fuel line in place.

4. Plug the fuel pump's three-pin connector into the wiring harness and fit the wire into the wire loom. Connect a fuel tank filled with a 50-to-1 mix of gasoline and outboard motor oil -- 2.88 ounces of oil per gallon of gas -- to the quick-connect on the priming bulb. Pump the priming bulb until it becomes firm and visually check for leaks in the system.

5. Replace the starboard-side lower engine cover.

Items you will need

  • Shop rag
  • Razor knife
  • Flathead screwdriver
  • Thread locker
  • Fuel pump
  • Zip ties
  • Torque driver
  • Fuel tank
  • Fuel -- 50-to-1 mixture of gasoline and outboard motor oil

Tip

  • The choice of replacement fuel pumps for the 90-horsepower Evinrude is reasonably broad. One is the pump from the 1983 50-horsepower Evinrude. A strong pump, it predated Evinrude's VRO2 and Accumix oil systems and has the same bolt pattern as the pump you're removing. Also, the fuel pumps from any of Evinrude's "commercial" outboards -- all of which are four-stroke engines -- are suitable.

Warning

  • Always disconnect the negative cable of your boat's battery before performing any maintenance work to prevent electrical shock or inadvertent starting. Remove the nut from the negative post with a 5/16-inch box-end wrench. Lift the cable from the battery, move it outside of the battery box and close the lid of the battery box. After the work is complete, reconnect the negative battery cable.

References

  • Evinrude Repair Manual -- 2.5- to 250-Horsepower Models, 2002-2007; Seloc Marine

About the Author

Will Charpentier is a writer who specializes in boating and maritime subjects. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. He is also a certified marine technician and the author of a popular text on writing local history.

Photo Credits

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