Re: disabeling VRO on evinrude 40
Just to reiterate, I've premixed and used the VRO/OMS system and prefer the VRO/OMS. I firmly believe that - for me - it is safer to maintain and monitor a VRO/OMS system than to pre-mix in my built in tanks. And I've been a pre-mixer since I was a kid in the 60s, so it's not like I"m unfamiliar with the process, calculations, etc. It's just easier for me to top off the oil tank (mine is quite visible, not to be forgotten!) than to figure out how much gas will be going into my tanks, measuring out the oil, mixing them through the funnel, etc.... but remembering if I've done it or not and/or supervising family or other helpers to do it right.
But opinions go both ways. Read this before you decide:
http://continuouswave.com/whaler/reference/VRO.html
But disconnecting is very easy. Just to flesh out what cubonfloats wrote above:
While you're still running the oil mixing pump, run premix gas to flush the raw gas out of carb bowls, fuel lines, filters, etc.
Cut oil line near the fuel pump, plug with a bolt and hose clamp. Make sure there's absolutely no air leaks. I personally recommend this rather than disconnecting the oil line and covering the nipple with a cap. I had a pump that was d/c'd that way and the rubber cap degenerated (rotted, cracked) and leaked air. The air leak caused performance problems, and can damage the engine due to lean fuel and resulting lean lubrication. I think the original oil hose, plugged close by with a bolt and clamp is just easier and better.
Unplug the wire harness from the fuel pump (will have 3 or 4 pins, probably 4).
Remove tank and disconnect wires running from tank to engine.
Tape and/or secure the loose wires and plugs in engine compartment so there's no chance of shorting.