Need an engine diagnosis
 

I have a Merc I/O, probably about 10 years old. It has been tuned up and has
been running fine. But it tends to stall at idle speed and sometimes will
stall when you throttle back after running at speed.
Carburetor problem? Dirt in the gas? Electrical? Something simple or should
I haul it to the service guy?
Thanks.


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Could be something simple like the idle mixture screw is set too lean.
Usually at the base of the carb, one for each carb barrel. Back it or them
out half a turn and see if that helps.

Don

"DS" wrote in message
t.ca...
I have a Merc I/O, probably about 10 years old. It has been tuned up and
has
been running fine. But it tends to stall at idle speed and sometimes will
stall when you throttle back after running at speed.
Carburetor problem? Dirt in the gas? Electrical? Something simple or
should
I haul it to the service guy?
Thanks.


--

It can be any of the causes you are mentioning, but disturbance in the fuel
supply is most likely.
Just my experience:
Unless you are very patient, have the service manual, the necessary tools
and test equipment (peak voltage tester, fuel press indicator, pressurized
air etc.); leave it to the service guy.
Find one that is well skilled and have experience from that type of engine.
Good luck!
John

"DS" skrev i melding
t.ca...
I have a Merc I/O, probably about 10 years old. It has been tuned up and
has
been running fine. But it tends to stall at idle speed and sometimes will
stall when you throttle back after running at speed.
Carburetor problem? Dirt in the gas? Electrical? Something simple or
should
I haul it to the service guy?
Thanks.


--

I would suspect vacumm or timing...



"John" wrote in message
...
It can be any of the causes you are mentioning, but disturbance in the
fuel supply is most likely.
Just my experience:
Unless you are very patient, have the service manual, the necessary
tools
and test equipment (peak voltage tester, fuel press indicator,
pressurized
air etc.); leave it to the service guy.
Find one that is well skilled and have experience from that type of
engine. Good luck!
John

"DS" skrev i melding
t.ca...
I have a Merc I/O, probably about 10 years old. It has been tuned up and
has
been running fine. But it tends to stall at idle speed and sometimes
will
stall when you throttle back after running at speed.
Carburetor problem? Dirt in the gas? Electrical? Something simple or
should
I haul it to the service guy?
Thanks.


--

Could be, in addition to the other suggestions, a worn float needle/jet. A
"rebuild kit" from an autoparts prob ably wouldn't cost more than $5-10.00.
If you can get it, just replace the float needle and jet and gasket (if you
must), and filter.
LD

"DS" wrote in message
t.ca...
I have a Merc I/O, probably about 10 years old. It has been tuned up and
has
been running fine. But it tends to stall at idle speed and sometimes will
stall when you throttle back after running at speed.
Carburetor problem? Dirt in the gas? Electrical? Something simple or
should
I haul it to the service guy?
Thanks.


--

Verify that your idle rpms in gear in the water is between 600 and 800 rpms.
It may be just that your idle is a little low.


--
Tony
my boats and cars at http://t.thomas.home.mchsi.com

-
"DS" wrote in message
t.ca...
I have a Merc I/O, probably about 10 years old. It has been tuned up and
has
been running fine. But it tends to stall at idle speed and sometimes will
stall when you throttle back after running at speed.
Carburetor problem? Dirt in the gas? Electrical? Something simple or
should
I haul it to the service guy?
Thanks.


--