I have a lawnmower that had been running fine. A week or so ago, it
started stalling out, just after I'd started running it.

It'd start easy, run for about 20 seconds, then sputter out. It did this
regardless of whether I was mowing anything or not. Load didn't seem to
have anything to do with it.

I was thinking "gas or oxygen", so I removed the air filter and it ran
fine. I then ordered a replacement air filter.

With the replacement air filter in place, I get the same behavior. It
starts easily, runs for a bit, then stalls. Without the air filter, it
runs fine.

Any ideas?



--
Of all the dogs I have known the terrier has the best memory for friends.
Even casual friends are not forgotten if once accepted. As for the
master, what can exceed the patience and fidelity of the terrier if
once his heart is given; and if he is a little jealous and exclusive,
after all that is not peculiar to dogs.
-T.F. Dale

On Jul 2, 1:21*pm, Jeff Dege wrote:
I have a lawnmower that had been running fine. *A week or so ago, it
started stalling out, just after I'd started running it.

It'd start easy, run for about 20 seconds, then sputter out. *It did this
regardless of whether I was mowing anything or not. *Load didn't seem to
have anything to do with it.

I was thinking "gas or oxygen", so I removed the air filter and it ran
fine. *I then ordered a replacement air filter.

With the replacement air filter in place, I get the same behavior. *It
starts easily, runs for a bit, then stalls. *Without the air filter, it
runs fine.

Any ideas?

--
Of all the dogs I have known the terrier has the best memory for friends.
Even casual friends are not forgotten if once accepted. As for the
master, what can exceed the patience and fidelity of the terrier if
once his heart is given; and if he is a little jealous and exclusive,
after all that is not peculiar to dogs.
* * * * * * * * -T.F. Dale

Its running rich, maybe the choke is on, carb adjusted to rich, plug
fouled, weak spark, float bowl is not completely shutting off, timing
key is bad from hitting a rock, or its old and valves are bad, im sure
there are other reasons.

On Wed, 02 Jul 2008 13:21:54 -0500, Jeff Dege wrote:

I have a lawnmower that had been running fine. A week or so ago, it
started stalling out, just after I'd started running it.

It'd start easy, run for about 20 seconds, then sputter out. It did this
regardless of whether I was mowing anything or not. Load didn't seem to
have anything to do with it.

I was thinking "gas or oxygen", so I removed the air filter and it ran
fine. I then ordered a replacement air filter.

With the replacement air filter in place, I get the same behavior. It
starts easily, runs for a bit, then stalls. Without the air filter, it
runs fine.

Any ideas?

Most carb difficulties come from the main jet being obstructed either
partially or completely and/or the needle valve/seat or float preventing
the proper level of fuel being maintained in the bowl. Not knowing what
motor/carb you have makes it difficult to speculate on why it runs with
the filter off and not on. Not knowing if the engine stalls because it is
getting too rich of a mixture or too lean makes it even more difficult.
If you've never had a carb apart you might just want to take it to someone
who has and can clean it, replace the needle and seat and gaskets.

Claude Hopper wrote:
Jeff Dege wrote:
I have a lawnmower that had been running fine. A week or so ago, it
started stalling out, just after I'd started running it.

It'd start easy, run for about 20 seconds, then sputter out. It did
this regardless of whether I was mowing anything or not. Load didn't
seem to have anything to do with it.

I was thinking "gas or oxygen", so I removed the air filter and it ran
fine. I then ordered a replacement air filter.

With the replacement air filter in place, I get the same behavior. It
starts easily, runs for a bit, then stalls. Without the air filter,
it runs fine.

Any ideas?



If the air filter was choking it out it wouldn't run for 20 seconds and
then choke out. It would stay flooded out from start. Something else is
going on. Is it an automatic choke? Is it a dry or wet filter?


Hmmm,
Fuel tank venting rpoblem? If filter is suspect run it without it to
prove. To test the fuel cap, loosen it up so air can pass and run the mower.

ransley wrote:
On Jul 2, 1:21 pm, Jeff Dege wrote:
I have a lawnmower that had been running fine. A week or so ago, it
started stalling out, just after I'd started running it.

It'd start easy, run for about 20 seconds, then sputter out. It did this
regardless of whether I was mowing anything or not. Load didn't seem to
have anything to do with it.

I was thinking "gas or oxygen", so I removed the air filter and it ran
fine. I then ordered a replacement air filter.

With the replacement air filter in place, I get the same behavior. It
starts easily, runs for a bit, then stalls. Without the air filter, it
runs fine.

Any ideas?

--
Of all the dogs I have known the terrier has the best memory for friends.
Even casual friends are not forgotten if once accepted. As for the
master, what can exceed the patience and fidelity of the terrier if
once his heart is given; and if he is a little jealous and exclusive,
after all that is not peculiar to dogs.
-T.F. Dale

Its running rich, maybe the choke is on, carb adjusted to rich, plug
fouled, weak spark, float bowl is not completely shutting off, timing
key is bad from hitting a rock, or its old and valves are bad, im sure
there are other reasons.
Hi,
If rich sound dof engine and exhaust color will tell.

If you don't have experience with engines (trouble shooting, repair), you
might be better off in the long run to just take it to a service shop and
let them deal with it. If you are handy with tools and know a bit about
carbs and electrical systems and engines, you might try to tackle it
yourself.

Do the basics first. Make sure the fuel tank is clean, and there is no
debris in it. Check the spark plug. Might as well replace it, spark plugs
are cheap. See if there is a fuel filter in line to the carb, check it to
see if it is plugged. Check the plug wire. Look for cracks, and make sure it
is clean. Inspect the throttle linkages and make sure they are all clean and
moving freely. Check hoses and wiring for obvious problems, cracks, etc.

Does it run good before it dies? If it does, then you can probably eliminate
mechanical failure. Make sure there is no grass build up
underneath. If you mow wet grass, you can get a lot of grass accumulating
there.

If it does not run good before it dies, then most anything could be wrong
with it.

If it runs normally before it dies and is easily restarted, then it is
probably not getting too rich. An engine that dies because it is too rich is
not easily restarted. My first guess would be needle/seat is sticking, float
bowl empties, engine stalls. It could be something in the float bowl that
blocks the main jet, but does not become lodged in it so that when the
engine dies, it falls out until you run it again. Even a leaking gasket
could do that. Does it backfire through the carb before it dies? Backfiring
through the carb/intake is a sign of a lean mixture.

Good time to take the carb apart and carefully clean it and replace all of
the gaskets if you know how to do this. That would be the first thing I do.
.. If you don't, see your local friendly lawn mower service shop and let them
deal with it.

If you know the carb is good and there are not leaks of fuel or air, and
nothing else is obviously wrong, time to take it to a shop. Based on your
description, my first guess would be a carb problem.


"Jeff Dege" wrote in message
. ..
I have a lawnmower that had been running fine. A week or so ago, it
started stalling out, just after I'd started running it.

It'd start easy, run for about 20 seconds, then sputter out. It did this
regardless of whether I was mowing anything or not. Load didn't seem to
have anything to do with it.

I was thinking "gas or oxygen", so I removed the air filter and it ran
fine. I then ordered a replacement air filter.

With the replacement air filter in place, I get the same behavior. It
starts easily, runs for a bit, then stalls. Without the air filter, it
runs fine.

Any ideas?



--
Of all the dogs I have known the terrier has the best memory for friends.
Even casual friends are not forgotten if once accepted. As for the
master, what can exceed the patience and fidelity of the terrier if
once his heart is given; and if he is a little jealous and exclusive,
after all that is not peculiar to dogs.
-T.F. Dale