I have got a used boat with a 1995 Mercury 115HP 2-stroke motor on it.
The motor has an oil-injection-system. This means in theory I don't
need to mix oil with fuel. But when I examine the fuel in the boat, I
find that the ex-owner has already mixed oil into the fuel. I am
wondering if the oil-injection-system really works or not. I would
like to find a way to check if the oil-injection-system works or not.

I supposed I can run the boat and keep an eye at the oil level in the
oil reservoir (knowing that the fuel already has oil and I don't need
to worry about running the motor without oil). If the oil level
gradually drop, this means the oil-injection-system seems to be
working, and I can feel free to add fuel without pre-mixing with oil.
If the oil level stands still, this means the oil-injection-system
fails, and I should pre-mix with oil and have the motor serviced. Does
this sound right?

And yes I need to carry more spare spark plus because the motor will be
running very rich with oil.

Thanks.

Jay Chan

You're a new boater as I have seen you ask many questions in this forum lately.

If I were you, I'd take the thing in to a Mercury mechanic and have them
check it out. Why run the risk of seizing the engine should the injection
system not be working?

For the peace of mind of it all, why not just have someone who knows the
engine take a look at it? You've worked too hard to get to this point.

barry

Well said. And while you're at it, have them change the water pump
impeller. Unless you know for sure it is less than 3 years old, you should
change it to be certain it is fresh. This is a wear prone part and the
price of leaving it too long is engine overheating and possible meltdown.

--
Denis Roy
D. Roy Woodcraft
www.ideasinwood.com
wrote in message
roups.com...

You're a new boater as I have seen you ask many questions in this forum
lately.

If I were you, I'd take the thing in to a Mercury mechanic and have them
check it out. Why run the risk of seizing the engine should the injection
system not be working?

For the peace of mind of it all, why not just have someone who knows the
engine take a look at it? You've worked too hard to get to this point.

barry

Mix appropriate fuel/oil mix in a six gallon can. Pull the hoses off
of the oil injectors and run the engine off of the pre-mixed oil. The
maintenance manual should outline this procedure and give you a rough
volume per injector to expect.

I am a bit confused with the suggestion. I guess the purpose of
pulling the hose off the oil injector is to make sure I would not
double-up with too much oil. But what does this have to do with
finding out the rough volumn per injector to expect? Please clarify.
Thanks.

Would the motor sound alarm if it doesn't get any oil from its oil
injection system?

I hope I will find out the answer from the motor maintenance manual
that I mail-ordered yesterday.

It may be that the oil injection system is deactivated, broken, or
that the previous owner hedged his bets by adding a little "extra" oil
in case of failure of the lube system. Small chance, too, that the
engine is newly rebuilt and needs this of "over lubrication" during
the break-in period.

I agree that this is not likely to be a case of "after rebuilt and need
to be over-lubricated". Otherwise, the seller would surely have
advertised the fact that the motor has been rebuilt recently -- this is
actually a selling point.

I hope this is simply a case of the ex-owner is hedging his bet. But I
would not surprised that the oil injection system is broken.

Since there is already oil in the tank..... it probably would be very
wise to figure out exactly *why*..... ignorance might turn out to be
really expensive....

I agree with this. I need to bring it in for service to see if the
marine mechanic can figure it out and maintain the motor.

Thanks for the suggestion.

Jay Chan

Well said. And while you're at it, have them change the water pump
impeller. Unless you know for sure it is less than 3 years old, you should
change it to be certain it is fresh. This is a wear prone part and the
price of leaving it too long is engine overheating and possible meltdown.

Because I will bring the motor in for service/maintenance, I will ask
them to replace the water pump impeller. Thanks for the suggestion.

Jay Chan

No. You are looking for the actual amount that the injectors would be
putting into the cylinders.... if they were still connected.
...
You may find a clogged injector or (if equipped) check valve.

OK. Now I understand your suggestion.

Would the motor sound alarm if it doesn't get any oil from its oil
injection system?

No. It would never know. It assumes... and this is the problem... that
if there is oil available in the tank, the system will work
properly... it CERTAINLY may not.

I see. Thanks for the warning. This means I cannot rely on the motor
to warn me.

I hope I will find out the answer from the motor maintenance manual
that I mail-ordered yesterday.

Read it thoroughly.... and I HOPE it is a FACTORY service manual....

No. It is a maintenance manual from Mercury for explaining things like
where the oil-filling plug is, how to replace lower unit oil, how to
change filters...etc. It is not a service manual for repair.

Jay, not to be an assh*le.... but, at this point in your education,
all of this seems a bit beyond your experience level.

I highly recommend that you enlist the services of a highly trained
mechanic to assess and diagnose the condition of your engine.

Mistakes, while highly educational, can, with marine engines, be
terrifically catastrophic and expensive. You are headed in the right
direction.... seeking information and learning about your new toy...
but don't make an expensive mistake in assuming you know more than you
do.......

Yes, I understand your point. I am just trying to find out if I really
have a problem or not. At this point, I don't really know if I have a
problem or not. If I really have a problem in the oil injection
system, I will bring it to a marine mechanic. If I don't have a
problem, I don't need to do so (unless I have some other things that I
need them to fix).

Thanks for the warning though.

Jay Chan