"Won't start" has multiple causes. First thing to do is to figure out
why it won't start. A good starting point is to squirt a bit of gas
into the intake and she if it tries to start. If it does try, then
you clean the carb. If it doesn't try to start then check to see if
you have spark.
That covers 99% of the no start problems on portable gas engines. For
specifics there is a Canuk on U-tube that does a really nice job with
a bunch of videos you can watch. see:
Spark, fuel, air.
Pull the sparkplug, lay it on top of the
head with the wire attached and confirm
you have a nice fat blue arc when you pull
the starter cable. If you don't get your
spark, you can have a look at the magneto
or whatever ignition system it has.
Ignition is a very popular failure mechanism
in small engines.
If you do get a nice fat blue spark, look
at the plug. Is the tip black and wet with
gas or dry and light tan in color?
If it is just gas fouled, you could yank
the cord a few times and dry out the
cylinder via the sparkplug hole.
Dry the plug, clean and gap. Try again.
Is the air filter clean?
If you get a spark and the plug looks OK,
consider shooting a little gas into the carb.
If it starts, you may have a plugged jet.
A carb rebuild is probably in order.
On Mon, 24 Oct 2011 22:50:16 -0700, Winston wrote:
Spark, fuel, air, compression,
Everything that Winston said, but if you get to the end of the "check
this" list and things still aren't working make sure that it draws air in
the intake during the intake stroke, that it exhausts air on the exhaust
stroke, and that it has compression. In other words, make sure that
there's still rings, and that a valve isn't stuck open.
I used to own a lawn mower that ran great, except that if you left it not
running for over a few weeks you had to whack the head with a 2x4 a few
times and try extra hard to get it to start. I'm pretty sure it was a
stuck valve (and a really lazy owner, to not fix same).
Control system and signal processing consulting
Yes. That too. :)
Beware that a compression test on a small 4 cycle
motor may read 'low' and yet be perfectly within
specification. The cam on some has a 'compression
release' feature to ease starting.
Presuming it's a gas engine a gummed up carb would be my first suspect.
Check for spark and compression first, but after that it's likely time
to teardown the carb and run it through the ultrasonic cleaner.
It seems everyone is going with cleaning the carb, which may or may
not be true. Your question is vague. Is it a 2 stroke or 4 stroke?
You are receiving answers for both which may not be correct. Before
you try anything that has been posted here, give more info or you
could be making the problem worse.
It could also be as simple as being flooded.
In my experience, the vast majority of the time it is
the carb because many of these home gas power tools
are used once in a blue moon, put away with gas in
them and it winds up gumming up the carb. Or the
fuels today with alcohol attract water which then rusts
up the needle valves, etc. I'm
wrestling with that exact problem now with a Stihl
chainsaw. If i used it every couple months, it would
But I agree, he should not rule out other causes. I
would have asked the seller if
A - Iit was running OK and then the same day it would no longer start
or quit while running
B - It was put away for two years and then would not
B - points to high probability of carb problem, A to
Your question is vague. Is it a 2 stroke or 4 stroke?
The major problem is that he bought a non-running saw. He has no idea
what is wrong with it. Now, the question is...... is it worth
If he likes to tinker, he can learn alot. But he better find out more
info before beginning.
Does Iggy like to tinker? You're new around here, I guess.
If it's a 4-stroke, you could try shooting some starting ether or
propane in the intake and see what you get. It's easy enough to check
for spark (and make sure the spark plug isn't soaked with oil or gas),
and as stormin' said, if you turn the motor backwards, you ought to
feel some compression.
But two-stroke or four, it's probably a fouled carb, and you can
probably fix it by soaking in gumout or methyl chloride.
If it's 2-cycle, then the problem is very likely the carb. Re-build
kits are less than $20. Walbro is the dominant carb maker. Service
manuals at http://wem.walbro.com/distributors/servicemanuals /
We would really need to know if this is a hand held, probably 2 stroke
engine, or a walk behind, probably 4 stroke engine.
A few things to try:
1. make sure that the fuel shut off is open
2. make sure that the ignition is on. Many pavement saws have more
If it is a 2 stroke saw, it is very easy to have too much oil in the
mix. It will NOT start if the mix is not correct, especially if it has
a too rich mix.
It never ceases to amaze me the prices that you pay for things. A
decent brand hand held cut off saw is over a $1,000. If it runs at all
it will bring several hundred.
Best one I head was sending the newbie all round the shop looking
for a box stretcher. Finally is sent up front to the manager's
office. He comes back a moment alter, embarrassed, followed by the
manager, who then reams the employees for sending him after the box
stretcher. "After all, we scraped the broken one six months ago!"
Go not to the Net for answers, for it will tell you Yes and no. And
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