On 7/5/15 6:17 PM, bob_villa wrote:
On Sunday, July 5, 2015 at 4:11:46 PM UTC-5, J Burns wrote:

I believe port blockage is a gradual process that reduces noise
and power, but the motor still starts normally. I've cleaned carbon
from ports and sometimes mufflers, but I've never had enough to
notice a loss of power.

Then this one should be written into the books...it would barely
start and stay at low speed. Nearly 100% blocked. I don't know what
they used for gas/oil mix?


.... or the gas/air mix. Mine can easily be set too rich, and it might
seem satisfactory. I set it as lean as it will still respond to the
throttle.

The OP said his problem happened suddenly. Mine has usually happened
because the screen got gummed by a material caused by getting moisture
in the fuel. It's hard to see because it's colorless and translucent.
It hasn't happened so much since I started mixing fuel 500ml at a time
in a 600ml soda bottle, so it's sealed against air and used pretty
quickly. I discovered that epoxy cement could seal the hole where the
fuel line exits the tank. That helped, too.

The second cause in my experience has been air leaks around a carburetor
gasket.

I found a third cause at my neighbor's this year. His fairly new trimmer
suddenly wouldn't run without the choke. He'd refilled it with fuel that
had been sitting in a milk jug a couple of years. When I finally
figured it out, I dumped the tank back into the bottle and filed it with
fresh fuel from my bottle. After it burned the fuel in the line and
carburetor, it ran like new.