1998 Johnson Evinrude "EC" 125C, 130, 200, 225, 250 90 deg LV Service Manual, P/N 520212, Page 87Get this manual
VRO Pump Operation
The VRO pump uses an air motor powered by crankcase pulses to drive fuel pump and an oil pumpThe fueloil mix is delivered to the carburetors under pressure
Pistons Move Right The air motor pistonfuel pistonand oil pistonall start from position all the way to the left in the VRO pumpAir Motor The VRO pumping cycle starts as pressure and vacuumfrom the pulse fitting pressure and vacuum rectifier valvescombine to pushpull the air motor piston to the rightFuel The air motor piston pulls the fuel piston which pushes fuel from the fuel outlet chamber through the fuel outlet fitting to the carburetors as it is used
Fuel is drawn in from the fuel tank through the fuel inlet fitting and fuel inlet check valve CD to the fuel inlet chamber Q)Oil Oil is drawn in by the oil piston from the oil tank through the oil inlet fitting CD, and through the oil inlet check valve Poppet Valve Opens When the air motor piston has traveled full stroke to the right, boss in the air motor cover pushes the poppet valve off its seat, connecting the air motor pressure and vacuum chambersPistons Move Left As the pressure in the two chambers equalize, the following things happen at the same time: Air Motor The air motor spring left