Vro pump, how to check

G DANE

Commander
Joined
Nov 24, 2001
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2,476
I just bought a 1988 Evinrude 40HP. Motor had been in water for 8 hrs, delivered to authorized dealer who rinsed and winterpreserved motor. Instruments in boat, battery, harness, starter and remotecontrol electric was damaged. The dealer wrote on the bill " perhaps change of VRO pump " As the owner and dealer could not agree upon costs of repair, the motor has been in workshop 2 yars and owners garage in 1 year.<br /><br />I checked compression and ignition - OK.<br /><br />Problem how do i know VRO function is good ?<br /><br />How do I disconnect VRO and run premix, and is it safer and smarter ?<br /><br />This is a looper, isnt it.<br /><br />Appreciate your advise
 

trevorcday

Petty Officer 1st Class
Joined
Dec 2, 2001
Messages
216
Re: Vro pump, how to check

Checking the VRO is a little dificult to describe without showing you. You need to remove the little electronic gaget held on to the end of the pump with tiny torx screws then remove the end of the pump housing. Holding your finger over the exposed fuel port you squeeze the primer bulb to pressurize the fuel line. If you see fuel leaking through the end of the VRO it is dead.<br /><br />The problem you are checking for here is a tiny crack that develops in the pump body. The crack allows the oil to become diluted with gas before it is metered by the pump. The end result is that the pump is dispensing less fuel than it thinks it is and the engine blows up. The warning beeper never goes off because the pump is pumping away fine.<br /><br />I would definately recommend disabling the pump.
 

jegervais

Chief Petty Officer
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Jan 18, 2002
Messages
646
Re: Vro pump, how to check

The service manual lists 2 static tests which can be done. This requires removal of the pump from the engine and you'll need a pressure and vacuum tester (the testers used to check gearcases work well). These tests will check the integrity of the units air motor diaphragm and rectifier valves. <br /><br />The other test which mrmerc suggested can also be done while the unit is off. Install a pressure tester to the fuel inlet and pressurize to 6 to 8 psi. This actually tests the integrity of the oil piston seal which usually causes the VRO to over-oil rather than dilute the oil with fuel. A complete failure of that seal could however cause fuel to get into the oil, but thats a pretty rare happening. <br /><br />There is also a running test which can be performed on the unit to determine its oil consumption. <br /><br />Having oil injection is a notable convenience, however the choice to disable it is yours. To disable, first remove the oil supply line from the lower motor cover (under the fuel line plug in) and securely cap the fitting so dirt, water or other contaminants can't get in and later gum up the works. Next, find the 3 or 4 wire harnes coming from the VRO and disconnect the amphenol connector (round, black rubber about 3/4" in diameter, about 2" long). This disables the "no oil" alarm and averts false warnings. Find the 2 wires from the oil tank and trace them to where the connect on the motor - disconnect them and pull the wires back to the tank, tape of any connections remaining under the hood of the outboard. Remember to pre-mix your fuel at a 50:1 ratio and that it.<br /><br />-John
 

G DANE

Commander
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Nov 24, 2001
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2,476
Re: Vro pump, how to check

Thanks John and MrMerc. <br /><br />It sounds a bit complicated, and i am new to both this motor and the system, maybe i should take it to the shop. Is failing VRO and blownup engines a weakness at these motors ? Is this motor looper or crosflow, -did they change the model i 88 ?<br /><br />Will disconnecting VRO harm the system, or can it be connected again. How does the fuelpump function when the power cord i disconnected ? Och this is many questions - thanks for your patiense.
 

jegervais

Chief Petty Officer
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Jan 18, 2002
Messages
646
Re: Vro pump, how to check

The VRO is both a fuel pump and an oil pump - it is operated by an air motor which uses a diaphragm and rectifier valves to convert crankcase pressure and vacuum pulses into motion for the pump's 2 chambers. The most common failure in a VRO is the air motor diaphragm, when it fails, the pump doesn't work - period. It won't pump fuel or oil and the motor doesn't run - a motor that can't run, won't blow up. The unit can and will pump water. Although it has a "no oil delivery" alarm it cannot tell what it is pumping. In fact, its still the only oil injection system on the market that features a "no oil" alarm. Therefore, checking the oil reservoir for water intrusion occassionally is a good idea.<br /><br />The other failure I've seen is the seal on the oil piston - when it goes it usually causes the unit to over oil. It can, if damaged badly enough cause fuel to get into the oil tank, but it is pretty rare. The VRO has a bad "rap" with alot of boaters due to inexperienced or unschooled "mechanics" who can't find a reason for a powerhead failure and point their finger at the pump. I've owned VRO equipped Johnson's since 1991 - although I've since sold them, I know the owners and they're still running fine. I only know of 2 bonified VRO failures we serviced at our dealership in the last 5 years. In my opinion, that's pretty reliable. If you ever hear someone say "My V-6 engine blew 2 cylinders, the mechanic said the VRO failed..." Thats a physical impossibility - the pump mixes fuel and oil and sends that mix to all the carbs. It cannot selectively oil (or not oil) 1 or more cylinders - whoever says that should find a new mechanic.<br /><br />Disconnecting it will not harm the system. The wires only purpose is to monitor the oil flow, it will have no effect on the fuel pump portion of the unit. If I disconnected it, I would be reluctant to put it back in service 1 or 2 years later. If you want to keep the oil injection feature, I would suggest a new pump (Bombardier recently made some "intelligent" changes to the OMC designed pump and it should really enhance reliability - but, they are pricey). If the fuel pump portion were to eventually fail, you could convert to a fuel only pump to save money. And lastly, that 45 cubic inch motor is loop charged (a looper).<br /><br />-John
 

letsbarbq

Petty Officer 1st Class
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Jan 6, 2002
Messages
241
Re: Vro pump, how to check

ok, i dont really know much about this topic, but i do know that i have a buddy that has disconnect that vro thingy and it is a 150 hp, johnson. he manually mix oil with gas. been running for past 6 months. no prob.<br /><br />i will let you know how he did it -- i'll ask when i see him. <br /><br />good luck.
 

Philby

Petty Officer 2nd Class
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Sep 28, 2001
Messages
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Re: Vro pump, how to check

John from Illinois<br /><br />Great post.!<br /><br />I think the VRO has had a bum rap . My dealer here in England says he has never had one go yet !! Again he has had problems blamed on the VRO that have not been VRO related .<br /><br />I persevere with my VRO and in my case I am more likely to forget to pre mix than have the VRO fail .<br /><br />John , this is a most informative post. Plenty of information and sound advice. The water ingress into the oil resevoir is a good point. I've had it myself. I've said it before :<br /><br />1/ Fresh oil every season.<br />2/ make sure its primed.and oil is visible in the see through thingy.<br />3/ make sure the alarms are working.<br /><br />Not saying they never fail, but if you read Johns comments I think the odds are a bit better stacked than people would have you believe.
 

G DANE

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Nov 24, 2001
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Re: Vro pump, how to check

John thanks for all your advise.<br /><br />I was just wondering. What if i cleaned tank hoses and connectors, and used the system. Can i premix in 1:75 i exa. and use VRO in the same time and watch the oil consumption to check the system. I would of course have too rich oil mixture, but avoid to harm the motor, and by mesuring fuel and oil consumption, i will know the system works. Good or bad idea.
 

jegervais

Chief Petty Officer
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Jan 18, 2002
Messages
646
Re: Vro pump, how to check

Evinrude & Johnson Technical Service recommend that ANY TIME the VRO pump or hoses are serviced (or any time the oil tank is drained and refilled) that you run a couple of tanks premixed at 50:1 until you determine the pump is drawing oil. I usually only put 1 gallon of oil in the tank and mark the level with a magic marker or piece of tape. Once you see that the oil level in the tank is going own it is permissible to go to straight fuel. (I do know a couple of paranoid individuals who run an additional 100:1 premix all the time - If they're happy, I'm happy!)<br /><br />Have a safe and fun boating season.<br /><br />-John<br /><br />One item to add, as Mr. Philby noted: Make sure the alarm system works!
 

trevorcday

Petty Officer 1st Class
Joined
Dec 2, 2001
Messages
216
Re: Vro pump, how to check

I beg to differ. We check all of the VRO motors that come into our shop as described above and the majority of them have a cracked pump housing allowing fuel into the oil. These are generally bullet proof motors once the VRO is disconnected.
 

ewr

Cadet
Joined
Sep 3, 2002
Messages
7
Re: Vro pump, how to check

OK GUYS what do you think about this!<br />i recently purchased a used johnson 1986 150 with VRO which is great, when i installed the engine i placed the oil bottle under the rear seat of the boat. ran the balance of my premixed gas thru the engine everything working great, started with the no mix gas, about the second or third time out as i was going across the lake the engine just stopped and acted as if it ran out of gas, i checked the gas line and started the engine up, took off and again it acted like it was out of gas, when i lifted the rear seat i discovered the oil line had become disconnected from the in-line bulb, (when someone sat down i think it pinched the bulb) i reconnected the oil line, pumped the bulb and nervously started the engine, it started right up and runs great, my question is, did i just get lucky or is there a shut down system so that if no oil is detected or a high temp sensor for shut down? what i did then is rerouted my line and put a piece of clear line from the engine to the oil bulb so i can visually see oil in the line.<br />Thanks <br />Earl
 

ob

Admiral
Joined
Aug 16, 2002
Messages
6,992
Re: Vro pump, how to check

You got lucky.Need to buy lotto ticket.
 
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