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Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 11079
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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Disconnected the VRO on my 50 hp Evinrude. Mixing 50:1

Customer Question

Disconnected the VRO on my 50 hp Evinrude. Mixing 50:1 oil/gas. Engine ran great in driveway with water muffs. Put in the water this morning, at full speed, engine seems like starving for gas. Lower speeds, engine runs great. Pumping Fuel bulb helps restore to full power.
Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.

Hello. You have one of 2 things going on a restriction in the boat side fuel system or a failing VRO pump. To determine which run the engine on a different fuel source. Get a can of gas mix oil in the fuel then stick the end of the fuel line coming from the engine into the tank. If engine runs better then you have a fuel restriction in the boat side fuel system. This can be debris in the fuel tank clogging the pick up tube. Clogged or kinked fuel vent of bad fuel supply line.

If no change then the VRO pump is bad and will have to be rebuilt or replaced.

Post back with questions and findings.

Customer: replied 1 year ago.
I did just replace the fuel fill line and vent line that goes into the tank from the side of the pontoon. Vent line is bent a little but didn't think it would cause obstruction.
Expert:  Tan replied 1 year ago.

The way to eliminate that as a possible cause is to remove the fuel cap and go run the boat.

A kinked vent line cuts off air to the fuel tank creating a vacuum as you use fuel. When you suck fuel out of the tank you have to let air in or that creates a vacuum starving the engine for fuel.

Customer: replied 1 year ago.
I'll try that. Along with a different fuel tank. Thanks Tan!
Expert:  Tan replied 1 year ago.

Your welcome.....Please don't forget to positively rate my help as that is the only way I get credit for helping you.

Follow up questions are always welcome.

Thank you...........Tan

Customer: replied 1 year ago.
Do they make some kind of flex hose I could put on the vent line?
Expert:  Tan replied 1 year ago.

You should have a loop in the vent hose this will keep it from kinking and keep water out. Water can get in the vent line through the fitting outside so they put a loop in the hose.

Expert:  Tan replied 1 year ago.

Here is an example of the way the fuel vent should be looped.