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Ski213

VRO or no VRO?

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Short history on my outboard. Bought the boat with some fuel issues. Outboard is a 97 Johnson venom. One of the issues was the fuel pump. I had heard a lot of this and that about VRO failures leading to under-oiling etc so I decided to have the VRO replaced with non VRO. It was a largely uneducated decision in hindsight.

Post VRO removal I got a lot of education courtesy of Way2slow on my outboard as well as from others. It sounds like the VRO was more of a scapegoat for problems unrelated to it than an actual problem itself. 

The Johnson runs great now, again in large part due to advice from here on a number of issues. I kind of feel like I made a mistake removing the VRO and I am considering going back to the VRO system. It's a totally stock motor, if it weren't I would probably continue premixing and go with the electric pump setup. I spend a lot of time wide open but I also idle a lot and I'm a little worried about carbon buildup from running 50:1 at idle. Maybe I shouldn't be. 

Should I just not worry about it and leave it alone or give serious consideration to going back to VRO?

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The bad thing about oil injection systems is when/if they decide to quit working they take your powerhead along with it, which is mega expensive if you can't rebuild that yourself (even if you can it's still expensive).  Tough call, but if you are doing fine as is now I'd just stay safe.  I like having the injection system but I worry about the day it fails and what it will cost me in parts and time for me to rebuild it.

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Yeah that's kind of the fence I'm on. If the fuel pump quits with pre mix I lean out and don't run. Not ideal to lean out but no doubt better than dropping the oil side of the VRO and continuing to run till something melts. It does seem like based on what I've heard the VROs fail on the fuel side first. Don't know for sure if that's actually the case and if it is if it's by design or luck. 

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OK, if you are talking about installing a 1997 VRO on the motor, then I would probably be a little hesitant .  If you are talking about buying coming off the big bucks and buying a new unit to install, I would say go for it.

A friend of mine worked for OMC as one of their technical trainers in Atlanta until the closed the doors in 99/2000.  They had redesigned the pumps for 1999 and make them about as bullet proof as they could be.  At the time, he referred to them as CRO pumps instead of VRO (Constant Ratio vs Variable Ratio) so if I was going to run one, it would be one made in 99 or later.  Somewhere before then they had changed them from a three wire to a four wire pump by adding a purple wire and supplied 12 volts to the alarm system instead of using the rectifier. 

The guy that was basically my mentor when I was learning to build the hot rod OMC's I build and was the guru of all OMC guru's at the time recommended against running the Oil injection at sustained rpms of  6,000 or more.  I actually run my modified motors at a 40:1 but they live a lot of their life at 6,500 to 6,600 rpm.

Now, if I was running a stock motor and not turning more than 6,000 rpm, I would probably run the oil injection for the convenience but at the $500-$600 they are going for now, that's a lot to pay for being lazy.  Especially knowing how much easier having a rotary vain electric fuel pump makes them to start.  My modified motors on the electric pump are as easy to start at my DFI motor.

 

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Just came here to post that on my '92 70 HP Johnson I had removed the VRO and went 50-1 and never had a problem.  Ran the motor for a good 12 years before the selling it.  Still running strong.  I'd continue mixing my oil over paying the $500 on a unnecessary item on a 19-year old motor.  Good luck with whatever you choose.   

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1 hour ago, Junk Fisherman said:

Just came here to post that on my '92 70 HP Johnson I had removed the VRO and went 50-1 and never had a problem.  Ran the motor for a good 12 years before the selling it.  Still running strong.  I'd continue mixing my oil over paying the $500 on a unnecessary item on a 19-year old motor.  Good luck with whatever you choose.   

As did I on my 1988 70hp Johnson. Sold that boat in 2004

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No VRO it is then. I thought about buying a used VRO and rebuilding it but it's probably still too much work and money than it's worth to not premix. Biggest concern for me was carbon buildup but it sounds like probably not an issue.     

Way2slow, we talked about the rotary vein awhile back and that's still on the table for me. Mine isn't terrible to start but it'd be nice to have FI starting ease. Is there a way to grab power for a relay that would only energize the relay when the flywheel is turning or do you just get power from the key switch?  

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I power a relay that runs the pump off the accessory side of the key switch, that way it's only on when the key is on and you don't have to worry about it being left on accidently.   My pump is mounted in the battery/bilge compartment in a place that's very easy to just unplug one of the wires that goes to it if I'm doing something where I want the ignition switch on but not the pump running.  If you have to mount the pump in more inconvenient spot, I would recommend running a wire from the accessory side of the switch to a switch, either on the dash or in the back, that you can turn the pump off when the switch is on.

I run a Carter 80gph, 7psi rotary pump and have never had to run a regulator or had a problem with it pushing the needles off their seats.  A good factory pump runs about 5-6psi and the motor can pull as much as 22gph at WOT and I like to at least double the gph required, so I wouldn't go below about 50gph.  The Carter pump I use draws about 6-7 amps and that's more than you can pull off the switch without burning it out so you need to go through a relay.  I just use of those generic Bosch style 4/5 pin relays that's used for fog lights and just about everything else you can think of. 

Once installed, you can forget about that dang primer bulb.  Launch to boat, drop the motor, turn the switch on, push the key in to prime if for two or three seconds (you will get a feel for what your motor needs) and start it up.  Mine are almost instant start when I crank start to crank it over.  That alone has always offset having to deal with measuring oil every time I add gas when running those motors.

Now, I've heard some say they have had problems with the electric pump pushing the needles off the seats (I think that's more the float levels being off)and some prefer to run the 15psi pump for more consistent pressure.  In both of those cases you need to run a regulator set between 5 and 6psi and the Carter or Holly regulators run about $30+.  If you run a regulator, I would recommend running it so when it reached pressure, it bled the excess  back into the tank and let the pump run all the time.  It's also common to run a fuel manifold with a feed for each carb coming out of it for more consistent flow to each carb and do away with all those T connectors, and the regulator in one end.  That keeps the pump from having to dead head against the regulator and using it's built in pressure relief but you have to run a second fuel line for a return line back to the tank and get it plumbed into the tank somewhere, either in the top of the tank or the vent hose or fill hose if you don't want to make holes in your tank.  A "T" connector in the vent hose is a good place to return it..

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