Minor Outboard Issues

[cbs]

Hi All,

Newby here again, :)

I recently bought a boat that came with a 2001 50hp yamaha 2 stroke oil injected motor.

The motor starts easily, runs well and smooth 99% of the time, has 150 or so hours on it (I am led to believe).

The only problem that I have experienced with it, is that on occaision, well after it has warmed up, when I open the throttle up to get on the plane it will stutter and occaisionally stall. A quick turn of the key will normally fire it back up and away I go. This does not happen on a regular basis. Yesterday, it probably happened twice over about a 2 hour period of running.

Suggestions?

Brett

[Spaniard_King]

needs a slight mixture adjustment, 2 strokes need to be slightly on the rich side at idle so when you throttle on (give it some air) it can accelerate accordingly.

Garry

[cbs]

Thanks Gary,

I trust that this might* be a simple adjustment somewhere that I have a go at myself?

This is my first outboard that I've owned, (after 25 years boating) so I've got something to learn a bit about now.


CBS

[davez104]

Being a 50hp, I would guess its multi carbie so probably a job for a good mechanic.

Dave.

[Roughasguts]

CBS, First thing I would have a go at is draining the carby's fuel bowls,
checking for water.

There should be a 13mm Hex head bolt down the bottom of each carb it may also have a spring between the hex head and the Carb.

Just undo that quite a few turns no need to pull all the way out, and catch the fuel in a small bowl as it comes out (if there is room)

What your checking for is water, or gunge.

Then prime the fuel bulb several times to flush the bowls.
Screw back Hex heads not to tight prime again check for leaks.

Also remove the spark plugs they can and will get dirty, either carbon or oiling up.
I would sugest carbon build up, just spray the plugs electrodes with carby clean.

Either clean or replace, and keep some spares in your boat.

[cbs]

Thanks Roughasguts

I'll give that a go, and look at swapping the plugs out.

Hopefully, there shouldn't be water there, as an inline water seperator is fitted to the transom,

cbs.

[blaze]

For the cost of spark plugs I would never recomend cleaning them, just buy new ones.
cheers
blaze

[kleyny]

what happens if you take off slowly untill the revs come up a bit then nail it???
i would say if it takes off without a hitch everytime you do this the idle mixture is out ;)
BUT if it still does it every now and again it sounds like fuel or spark.
how old is your fuel???
i'd replace the plugs anyway as blaze said then you know they are right

hope this helps

kleyny

[cbs]

Back again,

When I said I'd look at swapping them out, I really meant replace.

Most of the time there isn't a problem, I had no issue when accelerating after warming up when I first hit the water.

It seems more likely (in my mind) to happen after the engine has been running a while. First time it happened, was the first time I had run the boat, and was running is about 2+foot of chop in the broadwater (wind against tide) and slowed and stopped dead for perhaps 30 second then tried to accelerate to have it konk out. No problems restarting.

Fuel during this episode would have been a 50/50 mix of unknown(came with boat) and new fuel.

On the weekend the fuel would have been 6 weeks or so old, since I have done a complete strip, spray and refit. Could be something in that.

At this point, I think I'll swap the plugs, drain the carbs and run it again with the new fuel to see how it goes.

Boat is a 4.3m stessl if I haven't said it above.


cbs

[cbs]

Ok, I've removed the plugs and fitted new ones. The old ones looked clean, but brown with some oil on them. One had a small amount of carbon on it near the threads, but none on the electrode.

Also drained all three carbys (10mm screws) and pumped new fuel through. Didn't witness any real crud going through or water for that matter. Wasn't able to collect the fuel directly from the screw though to be sure.

With any luck, I've cured the problem, and at worst I've got a set of new plugs in and eleminated a possible problem.

Guess I'll find out next time I run it.

cbs

[kleyny]

hope all goes well for you and the simple things have fixed the prob.
let us know how it goes

kleyny

[Willdoe]

I had a problem something similar on a 70 merc, turned out to be the stator breaking down.
Willdoe