Oil injection removal question...95 mariner 175

[Embrey]

The guy I bought this boat off of a guy, and he said he had deleted the oil injection and mixed it himself. Which is what I have done all year. but I noticed gas fumes when opening the hull and some rainbow colors when draining the boat..lol. So I got to investigating. He had this tank cap stuffed up in the boat. One line t's into a line off the oil tank that is on the motor. The other goes into the bottom side of the block on a fitting. And he has bypassed the oil line on the other side. Now, I can hear like a check valve sucking sound coming from that cap when its running. I assume I need to plug that hose on the block and get rid of this tank cap. What is it for actually since it has a tank on the motor? Reserve tank? I know what i think needs done, but I'm not an expert on oil injection on these and I don't wanna end up frying pistons from blocking something off. And as of now, the motor runs great except if you take off slowly it will surge until it reaches about 20-30 mph ,then smooths out perfectly. If you stab the throttle its fine,and idles perfectly always and starts good. Just want this deleted right.

[Abbeysdad]

Anybody know what the advantage is in crippling the oil injection in favor of always mixing?
(I have an oil injected Merc 90HP OB with a 20+gal fuel tank and wouldn't think of hand mixing fuel/oil).

[BassBandit]

Originally Posted by Abbeysdad

wouldn't think of hand mixing fuel/oil).

Neither would I. My boat is oil injected so why fix it it ain't broken.

[Basscat7]

That cap is from the remote oil tank on the Merc ( mariner ), it was mounted in the bilge and held one to three gallons depending on the tank size. Would pump oil into the engine mounted small tank.
You can see the Cap on the left in the photo with the hoses attached that send the oil to the engine tank, the right cap is the tank fill cap.



If it was mine, I would look into finding a used tank, e-bay usually has a few, and hooking the oil injection back into place. Why have the bother of mixing oil and gas when you do not have to.

[Embrey]

ehh..its already all hacked up, and I'm not worried about mixing. Been doing it all year. Not that difficult. Just wanna make sure plugging the hole will work. but I've already plugged it. Theres no reason it should cause a problem. But I can see where leaving it open to air will. I just didn't know about it until now.

Originally Posted by BassBandit

Neither would I. My boat is oil injected so why fix it it ain't broken.

Well, when I'm doing 70 across the lake, I know its getting mixed fuel. If something breaks in the oil system and i don't know it, its gonna cost all kinds of money to fix the whole motor. And that's with me building it myself.

[Embrey]

SO...Does anybody else have any 'helpful' info on the plug in the side of the block? Just for peace of mind.

[champman]

The part you see on your engine is a check valve. It is there to pressurize the now missing oil tank . If you are not going to repair this system cap it off. That will stop engine pressure from being released, which may cause the engine sputter . F. Y. I. When everthing is working correctly, if the oil injection system stops working a buzzer or tone will sound.it is the sound you hear when the key is turned to on.at least it is like that on my champion, 175 merc.

[bamabassman]

Ok, i have a pontoon boat with a 70 hp evinrude with the automatic oil injection. It was capped off as well. The previous owner AND my boat repair shop said it was just fine to leave it that way. BOTH of them told me that the year model (1991) of my motor wasn't the best at injecting oil correctly. So it was capped off. I premix my fuel in this boat. Not a bad ordeal. If i am correct, it is because the oil injector would often times fail. Thus leaving oyu out on the water stranded. Must have happened to the previous owner quiet a few times to cap it off. So i haven't changed it back. Not worth the money in my opion. So i left it as it is. Works just fine for me.

[Embrey]

Originally Posted by champman

The part you see on your engine is a check valve. It is there to pressurize the now missing oil tank . If you are not going to repair this system cap it off. That will stop engine pressure from being released, which may cause the engine sputter . F. Y. I. When everthing is working correctly, if the oil injection system stops working a buzzer or tone will sound.it is the sound you hear when the key is turned to on.at least it is like that on my champion, 175 merc.

Yes, it is a one way check valve. I know there should be a buzzer, but I'm sure it was cut when this was taken off. So, I haven't heard a buzzer ever.

[lilmule]

The reasoning behind is is simple most oilers dont work correctly and will fail at speeds over 60 mph,mine is capped other than a lil extra oil at startup and slightly more smoke no problems.That surely does need to be plugged or else could suck some bilge water up it,if the check valve failed.
If you saw the oiler gears one would understand they are made of plastic,mine however is an OMC.
And quite a few older motors had no oil warning horn,just an overheat alarm.

[Embrey]

Originally Posted by lilmule

The reasoning behind is is simple most oilers dont work correctly and will fail at speeds over 60 mph,mine is capped other than a lil extra oil at startup and slightly more smoke no problems.That surely does need to be plugged or else could suck some bilge water up it,if the check valve failed.
If you saw the oiler gears one would understand they are made of plastic,mine however is an OMC.
And quite a few older motors had no oil warning horn,just an overheat alarm.

yeah, im looking into that too. im gonna try to locate the sensor and try to simulate a hot motor and see if it works. i want to make sure it works before i have to find out the hard way some day.

[lilmule]

While they arnt all plastic gears their design leaves lot to be desired at higher rpms,merc no exception.
But that said if operation is at or below 60 mph will do a decent job.They generally fail(omc) on the gas side first,as they do two functions oil and gas,resulting in a motor that runs at idle but not on plane.
The original part is costly,yet in most cases can be replaced by a 60 dollar pump,when it does go,as your not using the oil feature anyway if disconnected.
It does create more smoke on startup and prior to actual warmup of the motor, once warm you cannot tell it from viewing.

[Embrey]

What is OMC? im not familiar with that term.So, youre saying if the fuel pump craps out, just bypass it and run an inline electric pump?

[lilmule]

Evinrude,johnson-OMC corp,now known as bombadier
They make a pump to fit in place of the auto oiler on the motor if say a 150 hp and the number of carbs come into play,if not the external pump works as well.
On my xp 200hp wasnt possible had to buy the original part(or so my mech told me) then disconnected it,on my 150 gt it was replaceable with pump not pump/oiler.
My 200 venom came with an external so it can be done either way.(this he didnt tell me).
If external it needs to be within the psi required for the motor not over that psi,and yes most marine ones are common automotive name brands.
Eventually since it does both jobs will need to be replaced by one or the other,whichever one is applicable to your motor and or wallet,and preference.
Some motors lend more towards an external pump than others,some more to the gas pump versus oil gas pump,directly on the motor.Most however can be done either way,but ask your mechanic what needs to be done,as a part thats failed may come apart internally and go elsewhere,and may need to be removed or replaced with something.Possibly a plate that will install in place of ,with an appropriate fitting for the pump hose is all thats needed for external,again ask your mech whats possible,when and if needed to actually replace but there are many methods.
Now you already know of two different routes than the gas/oiler,both of which are cheaper,and tend to last longer.
For now just disconnect the oiler part and manually mix,they last quite a few years normally.My 1985 had to be replaced in 2008,and my 94 xp in 2009,my 94 venom knock on wood is external,but even if it went while out have two installed,other one is on a switch and does not normally run just there if needed.
The external has the added benefit of never having to squeeze that bulb and actually starts better.
I bought it that way previous owner was into racing somewhat,but it does have its advantages.
Its a 1990 2002 - Allison composite boat 900 lbs -20 ft,venom 200 hp,shorty (lower was made on a cnc machine)1.86 gear ratio,bobs nose cone 83 mph double loaded,full gas tank,altered to start in or out of gear,saves wear n tear on the gearcase.A lot of racer tricks come in handy,even if one runs around at 40 mph.No a 2002 isnt a great fishing boat as no storage up front,its designed to get you there to fish first,then get you back in less time than other boats.
That said I love mine as its slender shape avoids wind ,runs like a 21ftr in 2-2 /12 ft waves,and is easy on gas comparatively.

[Embrey]

Eh...when it happens, i'll figure it out. im a mechanic, so it cant be much of anything to bypass it. For now it works fine and probably will for who knows how long