2-stroke carburetor advice
Mr. Land
I wonder if there are any 2-stroke carburetor dudes out there who
could shed a little light on my situation:
I have a 2-stroke Weed Eater string trimmer that I've owned for quite
a few years. It has started and run flawlessly over the years, with
nothing needed from me other than filling the gas tank occasionally.
But this year, it suddenly wouldn't start. Being a cheapskate (and
loving to tinker) I disassembled the unit to try to determine the
problem. During my tinkering I discovered that if I poured a few
drops of gas/oil mixture down the carb throat, it would start and run
for a few seconds, so I decided it was a carburetor problem. I tried
pumping the primer bulb and that's when I realized that it wasn't
filling with fuel as it normally did.
After studying the design for a few minutes, I concluded that the way
priming works was as follows: the carburetor has two hose nipples on
one side of it. One hose connects to the priming bulb, the other
connects to the gas tank. A third hose runs between the gas tank and
priming bulb. When you pump the bulb, a vacuum is created in the hose
leading from it to the carburetor. That vacuum travels through the
carburetor internals, and out of the second hose nipple, connected to
the tank. As one continues to pump the primer bulb, this vacuum draws
fuel out of the tank and sucks it into the carburetor through the
second nipple. The fuel travels around inside the carburetor
("priming" it) and is eventually drawn out of the first nipple leading
to the primer bulb. The fuel enters the bulb and from there is pumped
back into the tank. This forms a sort of loop: as you pump the
primer, fuel travels down from the tank, into the carburetor, back out
of the carburetor through the other nipple, out to the priming bulb,
where it is pumped back up to the tank again. Does this sound right?
When I disconnected the hoses from the carburetor, the one leading to
the primer popped (indicating a vacuum), while the hose to the tank
squirted out gas (indicating a pressure build-up in the tank.) These
two facts led me to the conclusion that my carb was clogged.
I found a replacement on the web, ordered it and installed. Pumping
the primer then caused it to fill up with gas as it used to, and the
unit started right up. After a couple small adjustments it was
running like new. I was delighted and (a little too) proud of myself.
But then on the third use, I couldn't get it started again. I
disassembled it again, only to find the same symptom (no gas getting
"through" the carb) so now it seemed my brand new carb was clogged
also.
How far off base am I???
(thanks)
Tony Hwang
Hi,
Gas tank cap venting?
Tony
William W. Plummer
carburetor. You can purchase a rebuilding kit. I don't use all the
replacement parts in a kit, just the gasket.
DR, Bob
it will send the material it is made of (white felt like material) into the
carb, Inside the carb look for a screen (it will be the diameter of a pen)
if the fuel pick up is breaking down it will gather at the screen in the
carb, clean or replace the screen & replace the fuel pick up in the tank.
"Mr. Land" <graft...@yahoo.com> wrote in message
news:3a81cd7b.04071...@posting.google.com...
Stormin Mormon
out (cause then if you push the primer, the air squeeze would go out the
vent instead of pushing fuel). Just guessing, here.
But if the vent doesn't let air in, the system would starve for gas.
--
Christopher A. Young
Learn more about Jesus
www.lds.org
www.mormons.com
"Tony Hwang" <drag...@shaw.ca> wrote in message
news:OFnJc.23036$Mr4.1375@pd7tw1no...
> drops of gas/oil mixture down the carb throat, it would start and run
> for a few seconds, so I decided it was a carburetor problem. I tried
> pumping the primer bulb and that's when I realized that it wasn't
> filling with fuel as it normally did.
>
> "through" the carb) so now it seemed my brand new carb was clogged
Mr. Land
> Gas tank cap venting?
> Tony
Hello and thanks for trying to help.
Yes the cap on the fuel tank seems to be working properly. Just to be
sure I tried starting with the cap loosened...no difference.
I am beginning to wonder if I inadvertantly put some very old gas/oil
into the trimmer...which may have clogged the original carburetor (and
subsequently clogged the new one!).
Is there a known way to unclog a carburetor? Perhaps soaking it in a
can of some type of solvent?
Thanks again for any help...
m Ransley
clogged, air from a poor seal somewhere. Bad gas, drain it and it
should work through, so how did it start with a few drops if it was bad.
Use new gas and be sure you are not flooding it , ck for a wet spark
plug. Choke is on ?
DR, Bob
down the sparkplug hole with a flashlight to check if the sides of the
cylinder is scored, if it is then time for a new unit. If not that then
check my 1st answer.
"Mr. Land" <graft...@yahoo.com> wrote in message
news:3a81cd7b.04071...@posting.google.com...
Mr. Land
> My guess is you need to replace the gasket in the middle of the
> carburetor. You can purchase a rebuilding kit. I don't use all the
> replacement parts in a kit, just the gasket.
Hmm, that would make sense if I hadn't already replaced the entire
carburetor with a new one. As stated, the new one ran for a short
while, then exhibited the same symptoms.
Thank you for your reply.
Mr. Land
> the fuel pick up in the tank may be the fault here. If it is breaking down
> it will send the material it is made of (white felt like material) into the
> carb, Inside the carb look for a screen (it will be the diameter of a pen)
> if the fuel pick up is breaking down it will gather at the screen in the
> carb, clean or replace the screen & replace the fuel pick up in the tank.
>
Yes, I left that info out (figured my post was already too long.)
Inside the tank there is an off-white cylinder-shaped filter attached
to the end of one of the hoses (the one leading to the carb). As far
as I can tell it just rolls around in there...it doesn't seem to be
attached to anything other than the hose. It's definitely not felt,
though...it has the texture of fine sand that's been solidly
super-glued together to form a cylinder. I'll open up the new carb
tonight and look for that screen. Thanks very much for the ideas.
Mr. Land
I did find the screen in the carburetor...but it looked pretty clean.
It really seems likely that the fuel filter inside the tank is
emitting some debris which clogged my original carb before and has now
clogged the new one.
So I suppose my next move would be to fish out that filter and replace
it...but can I unclog the new carburetor? I tried disassembling it
and spraying it with solvent (paying particular attention to the
"needle" valve), but that had no apparent effect. If some orifice
somewhere is indeed clogged with a particle from the fuel filter...is
there any way to remedy that?
Thanks again!
"DR, Bob" <b...@mail.com> wrote in message news:<f_uJc.30926$Mr4.27495@pd7tw1no>...
Mr. Land
results.
Apparently, the solvent I first used to try to clean the carburetor
was ineffective. I re-cleaned it with a fresh can of carb cleaner
from my local parts store...and the trimmer is now purring like a
kitten (well, OK, a large, angry kitten.)
Sorry for so much bandwidth used for what turned out to be a simple
problem.
Edwin Pawlowski
> You all were so generous with your replies I felt obliged to post my
> results.
Thanks. Very few people ever get back with results. I did not contribute
to this thread at all, but I'm just happy to see someone took the time to
tell others the outcome.
Ed