[Pavel314[_2_]]

My old lawn tractor, that I use to haul stuff around the farm, has suddenly started running irregularly. It starts right up, but runs in pulses, increasing in RPM for about a second, then tapering off, then running high again, like a sine wave. It calms down a bit after a while but still runs with a noticeable pulsing. It ran well over the winter for hauling firewood, but with the warm weather suddenly went crazy. I suspect something in the carburetor so I put some gumout in the tank to see if that would help. Tomorrow I'll see if I can adjust the idler screw to calm it down. Any other ideas?

It's a Craftsman tractor, automatic transmission, 24 HP B&S two-cylinder engine.


Paul

[Terry Coombs[_2_]]

Pavel314 wrote:
My old lawn tractor, that I use to haul stuff around the farm, has
suddenly started running irregularly. It starts right up, but runs in
pulses, increasing in RPM for about a second, then tapering off, then
running high again, like a sine wave. It calms down a bit after a
while but still runs with a noticeable pulsing. It ran well over the
winter for hauling firewood, but with the warm weather suddenly went
crazy. I suspect something in the carburetor so I put some gumout in
the tank to see if that would help. Tomorrow I'll see if I can adjust
the idler screw to calm it down. Any other ideas?

It's a Craftsman tractor, automatic transmission, 24 HP B&S
two-cylinder engine.


Paul

If this is going on at low and part-throttle , it's probably a
partly/plugged jet . Give the gumout some time to work .

--
Snag

[Oren[_2_]]

On Tue, 8 Mar 2016 21:58:50 -0600, "Terry Coombs"
wrote:

Pavel314 wrote:
My old lawn tractor, that I use to haul stuff around the farm, has
suddenly started running irregularly. It starts right up, but runs in
pulses, increasing in RPM for about a second, then tapering off, then
running high again, like a sine wave. It calms down a bit after a
while but still runs with a noticeable pulsing. It ran well over the
winter for hauling firewood, but with the warm weather suddenly went
crazy. I suspect something in the carburetor so I put some gumout in
the tank to see if that would help. Tomorrow I'll see if I can adjust
the idler screw to calm it down. Any other ideas?

It's a Craftsman tractor, automatic transmission, 24 HP B&S
two-cylinder engine.


Paul

If this is going on at low and part-throttle , it's probably a
partly/plugged jet . Give the gumout some time to work .

A galloping or surging engine might be related to air or fuel
starvation, A good place to start. Loosen the gas cap and/or
clean/remove the air filter.

Look for a cracked line / vacuum hose.

[[email protected]]

On Tue, 8 Mar 2016 19:26:32 -0800 (PST), Pavel314
wrote:

My old lawn tractor, that I use to haul stuff around the farm, has suddenly started running irregularly. It starts right up, but runs in pulses, increasing in RPM for about a second, then tapering off, then running high again, like a sine wave. It calms down a bit after a while but still runs with a noticeable pulsing. It ran well over the winter for hauling firewood, but with the warm weather suddenly went crazy. I suspect something in the carburetor so I put some gumout in the tank to see if that would help. Tomorrow I'll see if I can adjust the idler screw to calm it down. Any other ideas?

It's a Craftsman tractor, automatic transmission, 24 HP B&S two-cylinder engine.


Paul
sure sounds like it is running lean. Make sure the carb isn't falling
off or apart.

[[email protected]]

On Tue, 8 Mar 2016 21:58:50 -0600, "Terry Coombs"
wrote:

Pavel314 wrote:
My old lawn tractor, that I use to haul stuff around the farm, has
suddenly started running irregularly. It starts right up, but runs in
pulses, increasing in RPM for about a second, then tapering off, then
running high again, like a sine wave. It calms down a bit after a
while but still runs with a noticeable pulsing. It ran well over the
winter for hauling firewood, but with the warm weather suddenly went
crazy. I suspect something in the carburetor so I put some gumout in
the tank to see if that would help. Tomorrow I'll see if I can adjust
the idler screw to calm it down. Any other ideas?

It's a Craftsman tractor, automatic transmission, 24 HP B&S
two-cylinder engine.


Paul

If this is going on at low and part-throttle , it's probably a
partly/plugged jet . Give the gumout some time to work .

Or the carb is loose or spme part of it, or a bad carb gasket.

ALSO

Check the governor. If it has the old governor plastic flapper, that
flapper could be gummed up on the shaft, or else it's coated with greasy
gunk making it heavy and and unable to move properly. Or the spring to
the gov is weak. Remember, the governor controls the speed, and pulsing
is often a symptom of a gov problem.

You can often check if it's the gov, by just holding it in place and see
if that stops the pulsing.

A 3rd but less likely problem could be burnt points or the condensor is
failing.

I'd start with the gov, hold it in a stationary place. If it still
pulses, look for anything loose on the carb. After that, it's a tossup
of whether to rebulld the carb, or replace the points and condensor
next. It probably needs a tune up anyhow.

[Stormin Mormon[_10_]]

On 3/8/2016 10:26 PM, Pavel314 wrote:
My old lawn tractor, that I use to haul stuff
around the farm, has suddenly started running
irregularly. It starts right up, but runs in
pulses, increasing in RPM for about a second,
then tapering off, then running high again, like
a sine wave. It calms down a bit after a while
but still runs with a noticeable pulsing. It ran
well over the winter for hauling firewood, but
with the warm weather suddenly went crazy. I
suspect something in the carburetor so I put
some gumout in the tank to see if that would help.
Tomorrow I'll see if I can adjust the idler screw
to calm it down. Any other ideas?

It's a Craftsman tractor, automatic transmission,
24 HP B&S two-cylinder engine.


Paul


When I took a small engine repar course, the instructor
called that "hunting" for the proper speed. The problem
is that the spring on the throttle att he carb gets
rusty and stiffens up. So, when the governmor tries to
regulate the speed, it swings too far. The answer is
to replace the springs at the throttle.

--
..
Christopher A. Young
learn more about Jesus
.. www.lds.org
..
..

[[email protected]]

On Wed, 09 Mar 2016 03:10:37 -0600, wrote:

On Tue, 8 Mar 2016 21:58:50 -0600, "Terry Coombs"
wrote:

Pavel314 wrote:
My old lawn tractor, that I use to haul stuff around the farm, has
suddenly started running irregularly. It starts right up, but runs in
pulses, increasing in RPM for about a second, then tapering off, then
running high again, like a sine wave. It calms down a bit after a
while but still runs with a noticeable pulsing. It ran well over the
winter for hauling firewood, but with the warm weather suddenly went
crazy. I suspect something in the carburetor so I put some gumout in
the tank to see if that would help. Tomorrow I'll see if I can adjust
the idler screw to calm it down. Any other ideas?

It's a Craftsman tractor, automatic transmission, 24 HP B&S
two-cylinder engine.


Paul

If this is going on at low and part-throttle , it's probably a
partly/plugged jet . Give the gumout some time to work .

Or the carb is loose or spme part of it, or a bad carb gasket.

ALSO

Check the governor. If it has the old governor plastic flapper, that
flapper could be gummed up on the shaft, or else it's coated with greasy
gunk making it heavy and and unable to move properly. Or the spring to
the gov is weak. Remember, the governor controls the speed, and pulsing
is often a symptom of a gov problem.

You can often check if it's the gov, by just holding it in place and see
if that stops the pulsing.

A 3rd but less likely problem could be burnt points or the condensor is
failing.

I don't think there has been a V twin Tecumseh, Briggs, or Kohler
engine built with points and condensor - al least not in th last 35 or
more years.

I'd start with the gov, hold it in a stationary place. If it still
pulses, look for anything loose on the carb. After that, it's a tossup
of whether to rebulld the carb, or replace the points and condensor
next. It probably needs a tune up anyhow.

[[email protected]]

On Wed, 9 Mar 2016 06:59:50 -0500, Stormin Mormon
wrote:

On 3/8/2016 10:26 PM, Pavel314 wrote:
My old lawn tractor, that I use to haul stuff
around the farm, has suddenly started running
irregularly. It starts right up, but runs in
pulses, increasing in RPM for about a second,
then tapering off, then running high again, like
a sine wave. It calms down a bit after a while
but still runs with a noticeable pulsing. It ran
well over the winter for hauling firewood, but
with the warm weather suddenly went crazy. I
suspect something in the carburetor so I put
some gumout in the tank to see if that would help.
Tomorrow I'll see if I can adjust the idler screw
to calm it down. Any other ideas?

It's a Craftsman tractor, automatic transmission,
24 HP B&S two-cylinder engine.


Paul


When I took a small engine repar course, the instructor
called that "hunting" for the proper speed. The problem
is that the spring on the throttle att he carb gets
rusty and stiffens up. So, when the governmor tries to
regulate the speed, it swings too far. The answer is
to replace the springs at the throttle.
That MAY end up being the fix, but I don't touch governor calibration
untill I'k 110% sure it isn't a fuel mixture problem.
Water in gas, dirt or corrosion (greenies) in jet, carb loose on
manifold, manifold loose on engine, something loose on carb etc.

In my experience other than a governor linkage being rusted solis or
restricted by an accumulation of crud, governor issues have been next
to non-existant. Fuel quality and backed off screws have been the VAST
majority of "hunting" problems - with fuel quality/restricted jets
being the majority of those.