Help-Mercury 9.9 Outboard Won't Run with Tank Connected

Help-Mercury 9.9 Outboard Won't Run with Tank Connected

Post by Brian Freema » Mon, 15 Jul 1996 04:00:00


Well spring has sprung and I still don't have the boat in the water.
I tried to start the old Mercury 9.9 Outboard and I am out of luck.
I would appreciate any help/advice from everyone out there who must
be smarter than me.

Symptoms:

1) Prime motor by twisting the throttle a few times.
2) Motor starts with gas tank disconnected.
3) Motor runs fine without gas tank for minutes at a time (until of
course the carb runs out of fuel).
4) Connect gas take it dies within 20 seconds or so.

This is repeatable (happened all afternoon).

I've replaced the fuel hose and cleaned the fuel filter in the motor and
in the gas tank.

Yes, I have fresh gas in the tank and new spark plugs.

I know that the fuel hose is in the correct direction because when I
squeeze the bulb I can get fuel coming out the carburator (btw, is this
supposed to happen ?)

I am wondering if I have clogged/stuck valve somewhere ? Last year the
brass part of the  
connector for the fuel line popped out (only a spring, needle and brass
fitting) so I reassembled and pushed them back in. This connection seals
and seems to work the same as before (i.e, push on the pin and gas comes
out and obviously goes in when the fuel line is connected).

Is there a rebuild kit for the carb ? Is this something the
mildly mechanically inclined should attempt ?

Any other suggestions ?

Thanks

Brian
(Boatless in New Jersey)

 
 
 

Help-Mercury 9.9 Outboard Won't Run with Tank Connected

Post by Marcus Be » Tue, 16 Jul 1996 04:00:00


says...

Quote:
>Symptoms:
>3) Motor runs fine without gas tank for minutes at a time (until of
>course the carb runs out of fuel).
>4) Connect gas take it dies within 20 seconds or so.
>I know that the fuel hose is in the correct direction because when I
>squeeze the bulb I can get fuel coming out the carburator (btw, is this
>supposed to happen ?)

No, it's not supposed to happen, and it speaks of a malfunctioing float
valve assembly. It could be worn, jammed, or blocked open with a
contaminant.

Hypotheses consistent with stuck float:
With the fuel line disconnected, the fuel pump just pushes air into the
carb, where it just escapes through the vent and the motor can run fine.
When you connect the fuel line, fuel starts pumping again, the carb
overflows with fuel, and the motor floods.

--


 
 
 

Help-Mercury 9.9 Outboard Won't Run with Tank Connected

Post by Jeff Nichola » Tue, 16 Jul 1996 04:00:00

Quote:

> Well spring has sprung and I still don't have the boat in the water.
> I tried to start the old Mercury 9.9 Outboard and I am out of luck.
> I would appreciate any help/advice from everyone out there who must
> be smarter than me.

> Symptoms:

> 1) Prime motor by twisting the throttle a few times.
> 2) Motor starts with gas tank disconnected.
> 3) Motor runs fine without gas tank for minutes at a time (until of
> course the carb runs out of fuel).
> 4) Connect gas take it dies within 20 seconds or so.

> This is repeatable (happened all afternoon).

> I've replaced the fuel hose and cleaned the fuel filter in the motor and
> in the gas tank.

> Yes, I have fresh gas in the tank and new spark plugs.

> I know that the fuel hose is in the correct direction because when I
> squeeze the bulb I can get fuel coming out the carburator (btw, is this
> supposed to happen ?)

> I am wondering if I have clogged/stuck valve somewhere ? Last year the
> brass part of the
> connector for the fuel line popped out (only a spring, needle and brass
> fitting) so I reassembled and pushed them back in. This connection seals
> and seems to work the same as before (i.e, push on the pin and gas comes
> out and obviously goes in when the fuel line is connected).

> Is there a rebuild kit for the carb ? Is this something the
> mildly mechanically inclined should attempt ?

> Any other suggestions ?

> Thanks

> Brian
> (Boatless in New Jersey)

Sounds like a stuck float to me...

 
 
 

Help-Mercury 9.9 Outboard Won't Run with Tank Connected

Post by bdfreema » Wed, 17 Jul 1996 04:00:00

Quote:


> says...

> >Symptoms:

> >3) Motor runs fine without gas tank for minutes at a time (until of
> >course the carb runs out of fuel).
> >4) Connect gas take it dies within 20 seconds or so.

> >I know that the fuel hose is in the correct direction because when I
> >squeeze the bulb I can get fuel coming out the carburator (btw, is this
> >supposed to happen ?)

> No, it's not supposed to happen, and it speaks of a malfunctioing float
> valve assembly. It could be worn, jammed, or blocked open with a
> contaminant.

> Hypotheses consistent with stuck float:
> With the fuel line disconnected, the fuel pump just pushes air into the
> carb, where it just escapes through the vent and the motor can run fine.
> When you connect the fuel line, fuel starts pumping again, the carb
> overflows with fuel, and the motor floods.

> --


That makes sense !!!
Any suggestions on how to unstick it ? I'll try some carb cleaner
but I suspect its time to get a manual.

Thanks for the help !!!

Brian

 
 
 

Help-Mercury 9.9 Outboard Won't Run with Tank Connected

Post by R.H. Defra » Wed, 17 Jul 1996 04:00:00

any suggestions on how to unstick it ? I'll try some carb cleaner
but I suspect its time to get a manual.

Thanks for the help !!!

Brian

Brian and others:

I recently pulled the three carbs off my Yamaha 40.  I took it slow
and easy, marking everything and taking a few notes. Gratefully, the
inside of these carbs was simplicity itself.  Didn't even need to
replace a gasket between the carb and the manifold because there is
an o-ring in a groove around the edge of the carb and all o-rings
were in good shape.

Anyway I took apart what could be taken apart and cleaned it all and
found nothing wrong with number 1 and number 2.  Gratefully number 3
had a stuck needle valve (looks like a pencil point plus about 4 mm
of pencil, but smaller?).  It was held in place by gas turned to
varnish (my terms).  It loosened up with a little rubbing and carb
cleaner and the motor runs great.  I have a Merc 9.9 that has been
sitting for two years.  I don't know how many carbs it has (probably
one?) and I am praying its as simple to clean up as the Yamaha
Mikuni's.  I used to have a YZ with a Mikuni which was a little more
difficult to clean up.  Perhaps it was all those birds and rocks I
sucked up off the desert floor?

Any suggestions from someone who has rebuilt the carbs on a Merc
9.9?  

R.H. Defran
Cetacean Behavior Laboratory
San Diego State University
San Diego, CA.  92182