Mercury 9.9 HP two stroke stalling at low idle
Cam Kelly
for about 1.5 months out of the water before I started to winterize
it. The gas/oil was also 1.5 months old (getting there but should not
be stale yet). The motor took a while to start which I expected. When
it did start it would stall after idling for about 30-40 seconds. If I
ran it a med-high throttle it would run fine, but at low speed it
would stall. If I pumped the primer bulb on the external gas tank as
it was stalling it would begin to purk up and continue. Any
suggestions would be appreciated.
Frederick Owen
It also had that problem after sitting a couple of months. My engine would
not pump up properly with the primer bulb.(It felt kinda mushy).
I replaced the plugs, sprayed some gumout in the carb and put stabil in the
gas and pumped up the primer bulb until I thought it was going to blow a
line and it finally quit doing it after I felt the bulb resistance lessen
all of a sudden. But I still had hard starting problems until I finally ran
out all of the old gas. Since then I run stabil in my gas year around and
the problem has not returned.
Don't know if this will help you but it's what I did to correct the same
problem.
"Cam Kelly" <camk...@canada.com> wrote in message
news:e166cbb1.02111...@posting.google.com...
That Larry
throttle plates closed is highest. Any air that can leak into the
crankcase makes it run too lean and it stalls. At higher speeds, the
crankcase vacuum is lower because you have the throttle plates open,
are loading it up with gas and the air leak has lots less effect on
mixture. Only at idle will an air leak cause the engine to run lean
when the throttle plates are closed and the fuel delivery is very low.
Look for a loose crossover hose, loose fuel pump hose, loose carb
gasket on either side of the reed box, any indication of oil blowing
out of the engine anywhere around it, especially under the flywheel or
any place the crankshaft is exposed. The airleak won't show up on any
compression test which tests the top of the piston, not the bottom.
Why don't outboard mechanics ever like to do a leakdown test for
airleaks??.....(c;
Larry
Scotty, did you mean to beam down the ignition keys
to the Enterprise? They showed up in my pocket.
Cam Kelly
Some additional information regarding this that may be important is
that I am running this in by driveway with a hose hooked to the
cooling intake. I have the motor on a home built stand. The gas tank
sits below and in front of the motor so the fuel line goes down from
the motor to the tank. When on the boat the tank is at level with the
fuel connector on the engine. I was reading another post last night
and someone was talking about the possibility of the fuel loosing
syphon because of this. Also the bulb doesn't go flat. It gets a
little softer but not much. I don't know how old the bulb is. I bout
the engine/tank used. I suspect that it is over 5-7 years old maybe
more. Any thoughts on this would be appreciated.
cam
Clams Canino
Assuming it didn't magicly lose compression or develop a crankcase vacuum
leak during the 1.5 months it sat, I'd guess it's a fuel system issue.
First you can try to put the can higher to simulate actual boat conditions -
there's a chance it just can't pick the gas *up* that far at a low idle.
Past that - cleaning the carb and replacing the gas outta do it.
-W
"Cam Kelly" <camk...@canada.com> wrote in message
news:e166cbb1.02111...@posting.google.com...
Dan Krueger
Try squeezing the bulb while the engine is off. It any gas leaks from the coupler, you have the same problem.
Dan
That Larry
point!
On Mon, 18 Nov 2002 19:32:39 -0500, Dan Krueger
<dankr...@mindspring.com> wrote:
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>Check the fuel line coupler where it connects to the engine. A friend of
>mine had this same problem. It turned out to be a loose, or pinched, o-ring
>inside the coupler. $5 later after a stop at Walmart and all was well.<br>
><br>
>Try squeezing the bulb while the engine is off. It any gas leaks from the
>coupler, you have the same problem.<br>
><br>
>Dan<br>
><br>
><br>
>That Larry wrote:<br>
><blockquote type="cite" cite="mid:3dd85ea8...@64.154.60.171">
> <pre wrap="">It's got an air leak. At low RPM, the crankcase vacuum with the<br>throttle plates closed is highest. Any air that can leak into the<br>crankcase makes it run too lean and it stalls. At higher speeds, the<br>crankcase vacuum is lower because you have the throttle plates open,<br>are loading it up with gas and the air leak has lots less effect on<br>mixture. Only at idle will an air leak cause the engine to run lean<br>when the throttle plates are closed and the fuel delivery is very low.<br><br>Look for a loose crossover hose, loose fuel pump hose, loose carb<br>gasket on either side of the reed box, any indication of oil blowing<br>out of the engine anywhere around it, especially under the flywheel or<br>any place the crankshaft is exposed. The airleak won't show up on any<br>compression test which tests the top of the piston, not the bottom.<br><br>Why don't outboard mechanics ever like to do a leakdown test for<br>airleaks??.....(c;<br><br><br><br>On 1
>7 Nov 2002 16:39:10 -0800, <a class="moz-txt-link-abbreviated" href="mailto:camk...@canada.com">camk...@canada.com</a> (Cam Kelly) wrote:<br><br></pre>
> <blockquote type="cite">
> <pre wrap="">I have a '92 merc 9.9hp 2 stroke that ran very well all summer. It sat<br>for about 1.5 months out of the water before I started to winterize<br>it. The gas/oil was also 1.5 months old (getting there but should not<br>be stale yet). The motor took a while to start which I expected. When<br>it did start it would stall after idling for about 30-40 seconds. If I<br>ran it a med-high throttle it would run fine, but at low speed it<br>would stall. If I pumped the primer bulb on the external gas tank as<br>it was stalling it would begin to purk up and continue. Any<br>suggestions would be appreciated.<br></pre>
> </blockquote>
> <pre wrap=""><!----><br>Larry<br><br>Scotty, did you mean to beam down the ignition keys<br>to the Enterprise? They showed up in my pocket.<br><br></pre>
> </blockquote>
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Larry