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Dominick
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I have a 1999 Mecury 115hp 2 stroke Outboard. The last time

Customer Question

I have a 1999 Mecury 115hp 2 stroke Outboard. The last time I was on the lake, I had an issue with the outboard stalling out on me. Upon starting the motor up it would stall out as soon as I would put it into gear and give it gas. I decided then to let it run for a bit with it in the neutral position with the throttle straight up and locked. After letting it run like this for a minute or two I was able to put it in gear and take off at any speed. During this same outing after having the engine off for an hour or two I encountered the same problem but had to disconnect the fuel line and reattach it which seemed to help. I just attempted to start it in my driveway with a flusher attached and had the same issue, but noticed that if i let it sit in neutral until a stream came out, It would not stall out. We had all the carbs rebuilt on it 2 summers ago and run only premium gasoline. It ran fine for an entire weekend when I had out the first time this season approximately 3 weeks before this issue developed..
Submitted: 1 year ago.
Category: Boat
Expert:  Charles replied 1 year ago.

Hello, my name is***** will assist you.

Would you please post the serial numbers of the engine?

Customer: replied 1 year ago.
the serial number is ***** 359 24 the model number is *****
Expert:  Charles replied 1 year ago.

Your serial number will start with a 0 then a letter, followed by 6 more numbers.

Customer: replied 1 year ago.
IT'S EITHER
06935924 OR OG935924 That's off the warranty. I'll go check in on the motor.
Expert:  Charles replied 1 year ago.

0G9, thats it.

Can you remove the fuel hose from the engine, then using the primer bulb, pump some of the fuel into a glass jar to check it for water or debris.

Customer: replied 1 year ago.
Just did it. Gas looks perfect.
Expert:  Charles replied 1 year ago.

No debris or anything?

Customer: replied 1 year ago.
nothing.
Expert:  Charles replied 1 year ago.

Would squeezing the primer bulb over and over keep the engine running?

Customer: replied 1 year ago.
we tried that. it seemed like it didn't want more fuel.
Expert:  Charles replied 1 year ago.

Was the bulb still firm?

Customer: replied 1 year ago.
Expert:  Charles replied 1 year ago.

Ok, can you pull the spark plugs and inspect the tips of them?

Customer: replied 1 year ago.
ok
Expert:  Charles replied 1 year ago.

Let me know how they look.

Customer: replied 1 year ago.
they all look like twins. not black , not white. Kinda of grey. here is a pic.
Expert:  Charles replied 1 year ago.

Not too bad. Do you also have a compression tester?

Customer: replied 1 year ago.
No I do not. I could get one. How do I use it? What should it read? Could this be a fuel filter? Its 3 years old.
Expert:  Charles replied 1 year ago.

If the engine stayed running and using the primer bulb made no difference, I dont feel that it would be the filter.

to use the gauge, remove all 4 plugs, then install the gauge on a cylinder, crank the engine over until the gauge reading reaches its max pressure. It should be over 90 PSI on each cylinder.

I am cooking dinner at the same time, so my replies may be a bit slower.

Customer: replied 1 year ago.
i will rent one in the am and test it. thanks for your help thus far.
Expert:  Charles replied 1 year ago.

Great, let me know what you get.

Customer: replied 1 year ago.
Charles,
We got 115 psi on all 4 cyl.
Customer: replied 1 year ago.
The boat has been out twice. The first time, was right after we took the boat out of Winterization. Ran great all weekend.
Son took it out last weekend, filled it up before doing so, and that is when the problem started.
Expert:  Charles replied 1 year ago.

Make sure that there was not water in the fuel that was bought. It is really easy to do so.

Customer: replied 1 year ago.
what would it look like if there was? I would imagine you'd see two layers? There was no visual inconsistency in the gas we took out of it.
Expert:  Charles replied 1 year ago.

Yes, there would be two layers. One clear and one amber in color.

Customer: replied 1 year ago.
nope, didn't see that. Anything else we can check?
Expert:  Charles replied 1 year ago.

Check the thermostat to see if it is stuck open?

Customer: replied 1 year ago.
Where would that be, what does it look like, and how do you check it?

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