I'm trying to help my daughter with her lawn mower (Sears, Craftsman). In
the past I've always been able to start them by spraying gas onto the air
filter. This time no luck. I have spark. The ignition is electronic. The
manual says that one of the possibilities is a loose blade. I have the
blade off the machine.
How would the engine know, or care, that the blade is loose or off?
Thanks, Ivan Vegvary
Richard (and your manual) are correct. The crankshaft will not have enough
momentum to get through the cycles and actually start running without the
blade firmly attached. And you'll feel the difference when you 'pull it
The other problem is you "spraying gas onto the air filter". Not only is
this a fire hazard, but it will also score the cylinder wall (sooner or
later). Definitely not good for your equipment.
I used the propane trickling into the carb trick the other day,
getting my lawn mower fired up for the summer season. Worked just
That's easy.... you're too dull witted to be capable of surprise. What
little synaptic ability you do possess is stretched to the limit with
life support. If you diverted power to the critical thought processors
you'd asphyxiate in a matter of minutes.
Once you have the blade back on if the carb has a foam air filter that
requires oiling you might make sure its oiled. When they dry out they
can allow the engine to run lean and be more difficult to start.
Ivan Vegvary wrote:
I'll bet you've got an exhaust valve stuck open. Has it been sitting all
winter and this is the first start? If the valve's stuck open, take the
head off and hit the stem with a little oil, tap it back down and turn the
engine through until it starts opening a closing normally. Hope this helps.
Make sure that the gas is brand new. Even if she ran the mower until
it was dry at the end of last season, there can still be old gas in the
carburetor bowl. If draining the tank and then putting in new gas
doesn't work, take the carburetor bowl off, drain it, clean it, put it
back on, and then try it again. You won't need to take the carburetor
off. Remove the plug to see if you have carbon between the electrodes.
This carbon can build up to the point where the gap disappears
completely. If you have a gap, though, you should be okay. Clean the
air filter. As a last resort, you can use starting fluid
_conservatively_, and understand that this might do more harm than
good, if you have not done everything else possible first. If all else
fails, move to Austin, and go into the music business. Just kidding.
Gary-take a look at the flywheels in vertical shaft rotary mowers and
in horizontal shaft motors. You will see an aluminum flywheel in the
rotary mower motor and a cast iron one in the horizontal one. And
another eye opener is to try to start that rotary mower without the
blade. Oftentimes what happens is that the motor, lacking enough
flywheel mass, will start to rotate backwards when it fires. When this
happens the handle will be torn from your hand instantly. DAMHITK.
Put the blade back on and the mower started on the first pull.
As recited by other posters, YES, without the blade the rope DOES get ripped
out of your hand and worse.
Thanks again. This is the best group for saving my bacon.
Maybe there is some truth to what you say but when I was a kid my dad and I
would make go karts with normal lawn mower engines (used a fan belt with a
90 deg twist) and they started just fine with no flywheel at all.
There is allot of truth to it. Maybe not all, but most lawnmower engines
need the blade attached to act as a flywheel. It is damned hard to even pull
some of them over without a blade as the engine will kick back.