You really need to put the oil pump back together and have the machine run the way it was intended - I know this sounds harsh but for all the time and trouble i takes to defeat the oil injection and keep replacing plugs you could get a pump that works and be back in action trouble free, if you can follow the charts that show the oil line routing try putting the OEM system back and mark the tank to see if it is drinking while you run on premix, the previous owner may have been overwhelmed in setting the marks for the cable or just thought because chainsaws do this it should be done in the marine world also - this is a long debate that I am not going to entertain, I have lawn care and marine 2cycle motor so I know where the smoke is welcome and where it is dicouraged. Using the OEM pump is a good idea for oil savings, you do not have to guess how much oil when you add gas away from home and burn the motor.