[Shop-talk] string trimmer engine won't run

[Battmain]

Sounds like fuel mixture issue to me if it will run with the choke partially open. Find the
manual online and mess with the mixture adjustment. It is usually pretty easy. If that
doesn't work, I'd get a carb rebuild kit or fuel diaphragm gasket and that should
resolve the issue. The diaphragm can also stick in the carb. Take the carb apart and look
at the flap on the diaphragm. It should be flexible and not stiff. If it's stiff, it wont meter
the fuel properly.  When you add more air by pressing the trigger, it needs more gas.
Sounds like it isn't getting it, which is why you need to keep the choke active.

Don't discount a crack in one of the fuel hoses. They can be hidden and be a RPITA to 
find. (Dont' ask how I know this.  :/ )  Also clean the spark plug with a dremel
and wire brush attachment if it has been sitting for a while, but I doubt that's the
issue here.

Brian
battmain at yahoo.com

----- Original Message ----
From: Brian Kemp <bk13 at earthlink.net>
To: Shop-Talk List <shop-talk at autox.team.net>
Sent: Thu, March 25, 2010 12:21:52 AM
Subject: [Shop-talk] string trimmer engine won't run

List,

(snip)
The fuel hose was replaced a year ago and looks in good shape.  The foam in the air cleaner was a bit dirty, so I cleaned it.  The carb looked like new.  The spark plug was fine.  I cleaned the mesh spark arrester on the muffler exit as it was pretty dirty.  I drained the fuel and looked at the in tank filter and it looked good.  Pushing the primer bulb gives the normal behavior of getting firm after 6 pushes, so I don't think there is any fuel delivery problem.  There are two adjustment screws on the carb, but since they have not been touched in 10 years, I wouldn't expect they moved.  I learned from my Triumphs that you don't play with carbs if they were working.
(snip)