I'm sure it's easy but a search through this group yielded little (so
far).

My mower sputters and spits, almost always at lower than normal RPMs.
RPMs vary constantly, and sometimes it comes very close to quitting.
It has, on a few times. This is all while on a level sidewalk, not
mowing or otherwise under any strain. It doesn't change when I start
mowing the grass.

I've cleaned the air filter and replaced the (very black) spark plug.
I have not taken this mower in to be tuned up in the 3 years I've had
it. Oh, it's a Briggs and Stratton 4.5 hp engine on a push mower (not
self-propelled); garden variety Lowe's purchase.

Any ideas on what next to check, change, adjust, or replace?

Thanks.

Greg wrote:
I'm sure it's easy but a search through this group yielded little (so
far).

My mower sputters and spits, almost always at lower than normal RPMs.
RPMs vary constantly, and sometimes it comes very close to quitting.
It has, on a few times. This is all while on a level sidewalk, not
mowing or otherwise under any strain. It doesn't change when I start
mowing the grass.

I've cleaned the air filter and replaced the (very black) spark plug.
I have not taken this mower in to be tuned up in the 3 years I've had
it. Oh, it's a Briggs and Stratton 4.5 hp engine on a push mower (not
self-propelled); garden variety Lowe's purchase.

Any ideas on what next to check, change, adjust, or replace?

Thanks.


The black spark plug is a clue. Black means that
it is getting too much fuel (rich). Have you
adjusted the needle in the carb (a screw and not
the idle screw), or maybe if fell out. Are you
really sure the air filter is clean, a dirty
filter is often the source of an over rich fuel
supply.
If you find the carb needle, while it is running
screw it in and the engine speed will increase, at
it's highest speed the fuel is too lean and just a
little more and it will start bucking so you back
it out a bit to the fastest speed and then back it
out a bit more because at a really lean setting
the engine will run hot.

One other possibility is there is something wrong
with the choke mechanism. A third possibility is
that something is sticking in the mechanism that
maintains the speed (usually two wires and a
spring connected to an air paddle) or that this
mechanism has been taken apart and put back
together incorrectly.

Greg wrote:

I'm sure it's easy but a search through this group yielded little (so
far).

My mower sputters and spits, almost always at lower than normal RPMs.
RPMs vary constantly, and sometimes it comes very close to quitting.
It has, on a few times. This is all while on a level sidewalk, not
mowing or otherwise under any strain. It doesn't change when I start
mowing the grass.

I've cleaned the air filter and replaced the (very black) spark plug.
I have not taken this mower in to be tuned up in the 3 years I've had
it. Oh, it's a Briggs and Stratton 4.5 hp engine on a push mower (not
self-propelled); garden variety Lowe's purchase.

Any ideas on what next to check, change, adjust, or replace?

Thanks.

Hi,
Sounds like running too rich. Tried with air cleaner removed?
Sure choke is off?

http://experts.about.com/q/Small-Eng...1746/index.htm


"Greg" wrote in message
ps.com...
I'm sure it's easy but a search through this group yielded little (so
far).

My mower sputters and spits, almost always at lower than normal RPMs.
RPMs vary constantly, and sometimes it comes very close to quitting.
It has, on a few times. This is all while on a level sidewalk, not
mowing or otherwise under any strain. It doesn't change when I start
mowing the grass.

I've cleaned the air filter and replaced the (very black) spark plug.
I have not taken this mower in to be tuned up in the 3 years I've had
it. Oh, it's a Briggs and Stratton 4.5 hp engine on a push mower (not
self-propelled); garden variety Lowe's purchase.

Any ideas on what next to check, change, adjust, or replace?

Thanks.

Nice site. Thank you for the reference.

--
Jim McLaughlin

Reply address is deliberately munged.
If you really need to reply directly, try:
jimdotmclaughlinatcomcastdotcom

And you know it is a dotnet not a dotcom
address.
"Arclight" wrote in message
...


http://experts.about.com/q/Small-Eng...1746/index.htm


"Greg" wrote in message
ps.com...
I'm sure it's easy but a search through this group yielded little (so
far).

My mower sputters and spits, almost always at lower than normal RPMs.
RPMs vary constantly, and sometimes it comes very close to quitting.
It has, on a few times. This is all while on a level sidewalk, not
mowing or otherwise under any strain. It doesn't change when I start
mowing the grass.

I've cleaned the air filter and replaced the (very black) spark plug.
I have not taken this mower in to be tuned up in the 3 years I've had
it. Oh, it's a Briggs and Stratton 4.5 hp engine on a push mower (not
self-propelled); garden variety Lowe's purchase.

Any ideas on what next to check, change, adjust, or replace?

Thanks.

I'd check the float and the gas tank for moisture etc. Try running it with
the gas cap off the tank also if it isn't allowed to get some air in the
tank it will do that.
"Arclight" wrote in message
...


http://experts.about.com/q/Small-Eng...1746/index.htm


"Greg" wrote in message
ps.com...
I'm sure it's easy but a search through this group yielded little (so
far).

My mower sputters and spits, almost always at lower than normal RPMs.
RPMs vary constantly, and sometimes it comes very close to quitting.
It has, on a few times. This is all while on a level sidewalk, not
mowing or otherwise under any strain. It doesn't change when I start
mowing the grass.

I've cleaned the air filter and replaced the (very black) spark plug.
I have not taken this mower in to be tuned up in the 3 years I've had
it. Oh, it's a Briggs and Stratton 4.5 hp engine on a push mower (not
self-propelled); garden variety Lowe's purchase.

Any ideas on what next to check, change, adjust, or replace?

Thanks.

My mower sputters and spits, almost always at lower than normal RPMs.
RPMs vary constantly, and sometimes it comes very close to quitting.
It has, on a few times. This is all while on a level sidewalk, not
mowing or otherwise under any strain. It doesn't change when I start
mowing the grass.

I've cleaned the air filter and replaced the (very black) spark plug.
I have not taken this mower in to be tuned up in the 3 years I've had
it. Oh, it's a Briggs and Stratton 4.5 hp engine on a push mower (not
self-propelled); garden variety Lowe's purchase.

Any ideas on what next to check, change, adjust, or replace?

Clean the carb.
Remove the carb and find someone with a parts cleaning machine, it would
save you from having to disassemble the carb and put it back.

One time my lawn mower wouldn't start after sitting around for years with
gasoline in it, I took out the carb, dunked it into an ultrasonic cleaning
machine filled with water and some kitchen grease cleaner. Minutes later it
looked very clean and after putting it back, the mower started up with one
pull. I also figured out a way to keep the carb clean:

everytime I finish using it, I shut off the fuel supply and let the engine
run until there is no gas in the carb. Then I put the mower on choke and
pull the start cord a few times to clear the carb. It's been several years
since I last cleaned it and I can still start it with one pull 90% of the
time. Not bad for a 15 year old john deere.