Johnson 2 stroke - excessive oil consumption

[Birdman84]

I have a 2005 Johnson 90HP 2-stroke that runs great, but recently noticed it is leaking oil from all 4 carbs (looks like more from the upper 2) down the mid section and out the bottom of the cover. The last few times I've been out I seem to be going through about 1 Gal. of oil for every 15-20 gallons of fuel. No problems idling, getting on plane, or at WOT. Starts and performs great, but it is smoking more than it did in the previous years. I don't run it much at low rpm's or store it with motor up. I am thinking the VRO may need replacement but because of the cost, I'd like to try some cheaper options first. Any ideas appreciated.

 

[oldboat1]

Wouldn't disconnecting the oiler be a way to go? Plug the oil line, and unplug the harness -- premix at 50:1 ratio. Good idea to use a portable tank to test.

 

[flyingscott]

I think you may have a couple problems. You should not have fuel leaking from the carbs maybe a needle and seat issue. A VRO when it is failing can start pumping to much oil. An air leak on the fuel side of the pump can also cause over oiling.

 

[Birdman84]

I've considered going to a straight fuel pump but I don't want to have to guess with pre-mixing oil, nor the risks whether small or large from converting. I can't see where any fuel is leaking out, just a heavy buildup of oil at the mouth of the carb throats. I took a piece of clear tubing and checked for air bubbles after priming but nothing noticeable and it's holding pressure fine. is there a better way to check for air leaks?

 

[dingbat]

The last few times I've been out I seem to be going through about 1 Gal. of oil for every 15-20 gallons of fuel.

Pretty hard to believe the boat would even run at a 15:1 ratio.

Orginal carb bowl gaskets?

When Is the last time you changed needle valves or adjusted the floats?

 

[flyingscott]

There is a test for the VRO pump google it to find it. That is a fuel mix sitting in the carbs not just oil.

 

[Birdman84]

So maybe start with a carb rebuild? I bought this boat about 2 years ago and haven't done anything with the carbs. The guy I bought it from was original owner but I'm not sure when the carbs were last worked on. I agree, hard to imagine the thing doesn't show performance issues with so much oil consumption but it hasn't missed a beat. I'll see if I can find the VRO pump test and try that out too

 

[racerone]

Find the test procedure in a factory manual.-----Basically run the motor on a temporary 50:1 supply.----Hooks up a clear oil intake tube on the pump to see how much oil is pumped over a number of pump cycles.

 

[dingbat]

So maybe start with a carb rebuild? I bought this boat about 2 years ago and haven't done anything with the carbs. The guy I bought it from was original owner but I'm not sure when the carbs were last worked on. I agree, hard to imagine the thing doesn't show performance issues with so much oil consumption but it hasn't missed a beat. I'll see if I can find the VRO pump test and try that out too

I would run the VRO test first and proceed from there. Something as simple as a sticking needle value will cause you to run rich.

No way to explain how you could be using almost 4X more oil that normal yet running OK

 

[Birdman84]

Had a mobile mechanic stop by yesterday who said he doesn't feel it's the carbs or fuel lines and said replace the VRO. He did find me a new replacement for $160 (not used). New one on order. Plan to do the VRO oil consumption test this afternoon so I can compare to consumption of new VRO unit. Will post results. Thanks for all the input.

 

[flyingscott]

I would double check the pump he is getting you because I bet it is a pre mix pump. That sounds like the price of an oil deleted VRO style pump..I have never seen a complete new VRO pump with the oil side to for less than 350. A.lot of techs will eliminate the oil side because they do not.like VRO.

 

[SweetD]

I agree that price seems too good to be true. But, as I mentioned on your other thread on THT, pre-mixing is not a bad thing. Let us know how you make out.

 

[cfauvel]

these things CAN be serviced somewhat

My oil consumption test videos
https://youtu.be/smF5JJ2mUWc
(with original brown flapper on fuel side)

https://youtu.be/YStE1PkqR0M
(with new flapper on fuel side)


if the motor runs well besides the oil consumption, deleting(plugging the inlet and disconnect the warning system) the oil side (with premix) is the simplest and cheapest.

That pump was designed for the motor specifically, to supply enough fuel as well as inject oil into the fuel .

Stuff coming out of the carb has nothing to do with the VRO...When pre-mixed fuel (which is what it would be at the carbs), evaporates, you're left with oil....so based on observing 'oil' as being your indicator that it is running too much oil is not sound.

Suspect the use of 1 gallon of oil for 15-20 gallons of fuel. ​​​​​​​You'd have to be precise in your measurements..

 

[Birdman84]

They do exist...
https://www.ebay.com/itm/Fuel-Pump-...m=273481438693&_trksid=p2060778.c100290.m3507

It's an aftermarket but for a fraction of the OEM price can't go wrong. If it ever fails me, I'm taking SweetD's suggestion and pre-mixing. Worth the reduction in headaches alone :facepalm:

 

[cfauvel]

They do exist...
https://www.ebay.com/itm/Fuel-Pump-...m=273481438693&_trksid=p2060778.c100290.m3507

It's an aftermarket but for a fraction of the OEM price can't go wrong. If it ever fails me, I'm taking SweetD's suggestion and pre-mixing. Worth the reduction in headaches alone :facepalm:

Be sure to do the following tests
Oil-consumption test
No-oil test (the most important one IMHO)
low-oil test

I suspect the aftermarket ones will be fine...they are pretty simple in design...it is a matter of the part materials. Who knows where OEM gets the parts....fo all we know...there is no difference between the OEM and aftermarket.

 

[jakedaawg]

I just scanned through the above points, forgive me.

1. While pre-mix is a valid option for some it is unacceptable. It's okay to want a VRO. I have many many folks who dont want to premix.

2. I have found that over oiling or excessive consumption is a common complaint. Many complain about too much smoke. In my experience, about 50% of the time it is solved with a better oil, they are not actually using more oil than they should, they are just using a cheaper smokier oil. Xd-50 seems to smoke alot less.

3. When one fails the consumption test a vro needs replaced. When it passes test but is using too much oil I almost always find a fuel restriction. Many times the restriction is not noticeable from the outside, its inside the fuel lines. Upon replacing all sections of fuel lines the problem disappears.

take it for what it's worth, hope it helps.

with the cost of new motors it's very important to get it right the first time. I would not trust a motor to an aftermarket vro or an oil side rebuild. The consequences are too steep financially.

if you choose a mechanic to solve this I hope he truly understands the Vro system. I have found that many incredibly experienced and otherwise magnificent folks dont really know and many base their opinions off of false assumptions and things they have heard and taken for granted.

 

[cfauvel]

^^^^^ know what he's talking about ^^^^^

 

[Birdman84]

Well I have figured it out so I wanted to share the culprit with all. I got the new VRO and installed it, the "NO OIL" alarm would consistently go off (I ran the motor on a separate pre-mix tank) The engine would starve of fuel after several minutes and die. It was clear the unit didn't work so I put the old one back on, engine ran fine, so I got a refund on the new unit. I was able to keep the "defective" VRO so, I took the old one apart and found the fuel pump diaphragm had a nasty tear in it. Used the new diaphragm from the spare unit and problem went away instantly. The smoke was dramatically less. It took me a while to take the old one apart from fear of messing something up but they are very simple to work on. Thanks all for the input, you all and this community are priceless.

 

[IDFISHER]

Awesome! Glad you got it solved and thanks for the update.

 

[JerEazy]

Nicely done.