Took my Yamaha 9.9 4 stroke out of storage (after 2 years) and tried to start it today.
It would not catch until I sprayed in some starting fluid, but then it would only
rev up a bit and then die. I think it is getting sufficient fuel from a supply tank,
but that is one thing to check. I ran the engine dry and fogged the carburator when I put
it away last time. Could the fogging material be blocking one of the jets? Do I have
to remove the carburator from the engine to clean it, or can this be done with the
carburator attached to the engine? I was using fresh fuel, and this is an almost new
engine, with about 20 hours on it. Somewhere I saw a recommendation to partially
or fully cover the air inlet to assist in getting fuel to the engine. Is that a good idea?

Sherwin D.

On Fri, 15 Jul 2005 23:59:22 -0500, sherwindu
wrote:

Took my Yamaha 9.9 4 stroke out of storage (after 2 years) and tried to start it today.
It would not catch until I sprayed in some starting fluid, but then it would only
rev up a bit and then die. I think it is getting sufficient fuel from a supply tank,
but that is one thing to check. I ran the engine dry and fogged the carburator when I put
it away last time. Could the fogging material be blocking one of the jets? Do I have
to remove the carburator from the engine to clean it, or can this be done with the
carburator attached to the engine? I was using fresh fuel, and this is an almost new
engine, with about 20 hours on it. Somewhere I saw a recommendation to partially
or fully cover the air inlet to assist in getting fuel to the engine. Is that a good idea?

Sherwin D.

If an engine starts with ether, not otherwise, its a fair bet the fuel
supply or carburettion is faulty.
One at a time then:
1) fuel pump working? Pulsing fuel out of an open hose?
2)Is this a float chamber carb? If so, has the float stuck up?
Has the float needle stuck up?
3) Has the inlet manifold sprung a giant crack? A little leak?

.....you get the picture.

Brian Whatcott Altus, OK

sherwindu wrote:

Took my Yamaha 9.9 4 stroke out of storage (after 2 years) and tried to start it today. It would
not catch until I sprayed in some starting fluid, but then it would only rev up a bit and then
die. I think it is getting sufficient fuel from a supply tank, but that is one thing to check.
snip Sherwin D.

Sherwin,

I went through a similar problem with the Yamaha 9.9 4-stroke on my Catalina 27
earlier this year. BTW, I usually use gasoline squirted into the air intake on
the carburetor rather than starting fluid because the starting fluid
can be hard on the engine. I fill an oil squirt can with gas and apply a
couple of squirts into the air intake when I want to start it. Obviously be
careful with the raw gas, and don't get a fire started.

You can convince yourself that there's a problem with your fuel delivery by
keeping the motor running with carefully timed squirts of gas from your oil
can.

If the engine runs when you squirt in gas, and then dies when you quit, there is
a problem in your fuel delivery system somewhere. Did you pump the primer bulb
really well to make sure that fuel got all the way to the fuel pump? If so, it may be
that your fuel pump membrane has cracked, and is not pumping fuel to the carb. You can
check this by unclamping the fuel line that runs from the fuel pump (back of the
engine) to the carb at the fuel inlet barb on the carb, and cranking the engine.
If fuel comes gushing out, the pump is working, and the problem is with your carb.

If the problem is with the carburetor, it is likely that both the idle and main jet
are plugged with fuel debris. If either jet were clear, the engine would get enough
fuel mixed in the air to allow it to run although possibly not like it should.

Copy and paste the following link into your browser, and it will bring up an exploded
view and parts listing for the 1996 Yamaha 9.9HP 4-stroke carburetor.

http://www.boats.net/yamaha/partsyst...5dc715ee20c05c

You should be able to find a similar diagram and parts listing for _your_ carburetor on
this site as well. If you are mechanically inclined, you can take the carburetor off,
clean it out with lacquer thinner, unplug the jets, and reassemble it. If you are _really_
careful, you can do all of this and still use the original gaskets--I did ;-) You'll
need to use a small piece of wire to run through the jets to clean out the crap. These
are the parts labeled 8,9 (Main jet and nozzle), and 5 ("pilot" = idle jet) in the exploded
drawing. I use q-tips dipped in clean lacquer thinner for cleaning the inside of the
housings. Don't get the lacquer thinner on the plastic parts or the gaskets.


If you are not mechanically inclined, this is the time to get re-acquainted with your
favorite outboard mechanic and get ready to cough up some bucks. Note that a whole new
carb only costs $301.49 + shipping, so don't let the outboard shop gouge you for more than
that to rebuild your old one.

Good luck with it,

Don W.

sherwindu wrote in
:

or fully cover the air inlet to assist in getting fuel to the engine.
Is that a good idea?


Wanna bet the inside of the float carb looks like it's coated in shellac
from the evaporating fuel left in it? Running it until it stalls only gets
part of the gas out of the float bowl. The rest turned to shellac and
clogged the jets so it runs way too lean.

Government bureaucrats and Greenies made this worse by demanding
manufacturers limit how far you can screw the jets in and out...as if that
made any difference in the pollution of the planet from jet aircraft and
power plants and solar wind. So, you can't unscrew the main jet any more
until it melts the shellac away like you "ustacould way back". The main
jet isn't even adjustable and the idle jet only turns half a turn.....how
stupid.....

--
Larry

Hi Larry,
You are possibly right about the floats, although in preliminary discussions with
outboard mechanics, they point the finger at the extremely fine jets in the 4-stroke
engines. One mechanic said gasoline dries to a powdery residue, which then can
become imbedded in these jets. This problem seems peculiar to 4-stroke engines.
My former 2-strokes never needed a carburator cleaning or rebuild. Why is this
sensitivity of 4-strokes one of the world's greatest secrets? I would have taken
extra pains to run something like 'Stabil' through the carbs before storing the engine.
I might have not bought a 4-stroke if I thought they would be so problematic. I
checked the engine today and gas is definitely coming out of the hose that supplies
the carborator. I will probably have to get my boat towed to the nearest mechanic.
I hope they don't have to remove the engine from the boat to do this job.

Sherwin D.

Larry wrote:

sherwindu wrote in
:

or fully cover the air inlet to assist in getting fuel to the engine.
Is that a good idea?


Wanna bet the inside of the float carb looks like it's coated in shellac
from the evaporating fuel left in it? Running it until it stalls only gets
part of the gas out of the float bowl. The rest turned to shellac and
clogged the jets so it runs way too lean.

Government bureaucrats and Greenies made this worse by demanding
manufacturers limit how far you can screw the jets in and out...as if that
made any difference in the pollution of the planet from jet aircraft and
power plants and solar wind. So, you can't unscrew the main jet any more
until it melts the shellac away like you "ustacould way back". The main
jet isn't even adjustable and the idle jet only turns half a turn.....how
stupid.....

--
Larry

Lionheart has a 5hp Nissan driving a 12' Fold-A-Bote. You're right about
the tiny carbs. Too tiny. The throat of it is about the size of a pencil.
All the components are very tiny, indeed, including jets. Diesel-fuel-in-
a-can like Stabil is nonsense. Save money and just put diesel fuel into
the float...same stuff. Gas doesn't "go bad" unless you let the tank
breathe in and out so the lighter elements can escape, leaving behind the
heavies. There's a 1987 Honda 5KW genset in my shed that has gas in it
from Hurricane Hugo in 1989 in a STEEL tank. The tank is kept full with
new gas, probably a pint. It will crank on the 2nd pull on 1989 gas.

If you're going to run the engine a lot and leave it in place, 4-stroke is
fine. Running it will keep the tiny float carb clean. But, if you're
going to transport it a lot or use it infrequently, I think a SIMPLE 2-
stroke that doesn't have some damned computer that requires a systems
analyst with special equipment to repair is much better. Premix gas has
OIL in it. OIL doesn't evaporate when the gas does, keeping the carb all
greasy and protected. The 10:1 in that Seagull protects everything from
the tank to the exhaust, covered in a film of motor oil. Doesn't take a
rocket scientist to see why.



sherwindu wrote in
:

Hi Larry,
You are possibly right about the floats, although in preliminary
discussions with
outboard mechanics, they point the finger at the extremely fine jets
in the 4-stroke engines. One mechanic said gasoline dries to a
powdery residue, which then can become imbedded in these jets. This
problem seems peculiar to 4-stroke engines. My former 2-strokes never
needed a carburator cleaning or rebuild. Why is this sensitivity of
4-strokes one of the world's greatest secrets? I would have taken
extra pains to run something like 'Stabil' through the carbs before
storing the engine. I might have not bought a 4-stroke if I thought
they would be so problematic. I checked the engine today and gas is
definitely coming out of the hose that supplies the carborator. I
will probably have to get my boat towed to the nearest mechanic. I
hope they don't have to remove the engine from the boat to do this
job.

Sherwin D.




--
Larry

sherwindu wrote:

One mechanic said gasoline dries to a powdery residue, which then can
become imbedded in these jets.

I though smoking dope in outboard shops was prohibited. It is
corrosion or other residue clogging the smaller jet size. It comes
down to what Larry said but there's no such thing a powdery residue
from clean gasoline evaporating.

In article .com,
wrote:

sherwindu wrote:

One mechanic said gasoline dries to a powdery residue, which then can
become imbedded in these jets.

I though smoking dope in outboard shops was prohibited. It is
corrosion or other residue clogging the smaller jet size. It comes
down to what Larry said but there's no such thing a powdery residue
from clean gasoline evaporating.

The old highest-test Sunoco (260?) blue dye regularly gummed up Mikuni
carbs on motorcycles. (that was back in the 70s, when Sun had 7 or so
different grades.)

I doubt that any of the current dyes are so coarse or injectors would
foul, but a small 4-stroke carb could be pretty sensitive. Still, I
suspect the mechanic was remembering the bad old days.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

Jere Lull wrote in news:jerelull-
:

I doubt that any of the current dyes are so coarse or injectors would
foul, but a small 4-stroke carb could be pretty sensitive. Still, I
suspect the mechanic was remembering the bad old days.



Put 3" of brand new gas in a gas can.....

Sit it out in the sun so the gas will boil off like it does in your float
carb....

Notice it's STILL GAS that leaves shellac in its wake....

--
Larry

Larry wrote:

Put 3" of brand new gas in a gas can.....

Sit it out in the sun so the gas will boil off like it does in your float
carb....

Notice it's STILL GAS that leaves shellac in its wake....

But not powdery residue - unless it's been used as a solvent for other
illegal purposes in said shop. :-)