(Might have the answer... but it's on the bottom)

It is a Briggs
& Stratton, about 5 yrs old, and gets medium usage. It has given me no
problems until now.
CY: OK, so it's fairly recent.


The cylinder appears to be getting a fuel/oil mix delivered but is not
getting spark.
CY: So, it's two cycle?


CY: I may be mistaken, but I think now days the coil and ignition module
are
all part of the same assembly. So, if the ground wire isn't killing it,
and
the magnet is spinning past th e coil, you should get spark. If not, you
replace the coil and module assembly.

'Walking' lawnmower.

4-cycle? Not sure - I don't have to pre-mix oil and gas. (see more below.)
CY: If it's got a dipstick and crankcase, that's a "4-cycle".


I replaced the coil/ignition assembly and now have spark back at the plug.
Unfortunately, it still won't start.

I have left the plug connected to the plug wire and grounded out the 'body'
of the plug and seen what appears to be consistent and good spark when
cranking the engine. There is fuel getting to the cylinder because I see it
on the plug when I pull it after cranking. I can't understand why I would
have two different failures at the same time.
CY: Might be just one....


I am going to change my gas
out and see what happens. (I usually run the mower off of the same oil/gas
mix I run through the weedeater. One of the mechanics at a lawnmower shop
suggested it and said the mower engine would actually last longer for it.)
CY: I can't comment on that, but it shouldn't hurt.


Q: Even though I see the plug sparking when I pull the start rope, can a
plug still be 'bad' and part of my problem?
CY: Yes, possible, but not very likely.

I think it is a Champion
RJ19LM. The manual sez that in some places (e.g., CA) the plugs will have a
resistor in them to reduce EMI emissions. If the place I am buying the plug
has any idea whether the plug has a resistor I will try to get the
non-resistor version.
CY: Champion did have some quality problems.


My manual for my Ryobi line trimmer at least came with directions on how to
adjust the carburetor but this manual for the Murray mower / B&S engine
unfortunately doesn't have any such information. I'll start with a new plug
unless people here feel that mine is good.
CY: Saving the best for last. If you hit a rock, the flywheel keeps going.
Shears a soft metal "key" and rotates out of tiem with the rest of the
motor. On the older mowers, that means no spark. Cause the magnet on the
flywheel is now out of time with the points. On the new electronic mowers,
you stillg et spark. But it's out of time with the cylinder. The way to
check is to pull the motor cover off the top. Take the big nut off the
center of the crank shaft (hold the blade with your boot under the deck
while you're cranking on the nut). Look down from the top. there should be a
notch in the crank shaft, and a notch in the flywheel. And they should be at
the same place. If the two notches aren't lined up, you need a new flywheel
key. Which is a whole new adventure.....


Thanks.
CY: Y'welcome.