On Monday, October 22, 2018 at 12:29:44 PM UTC-4, wrote:
On Mon, 22 Oct 2018 07:11:22 -0700 (PDT), trader_4
wrote:

So, about six months ago I reported on by success fixing the leaf blower.
That had a bad carb and stuck piston ring. So, I finally decided to do the
same with the Troy-Bilt convertible weed whacker. (It has a shaft that
converts between whacker and a lawn edger widget). It hasn't run in a
decade. IT is still in really good shape, wasn't heavily used.

I took the carb apart and first thing, the fuel hoses were shot, disintegrating.
The carb had a little bit of fuel gunk in it, not surprising since it was left
with fuel to evaporate all that time. I fully disassembled it, except for
removing one welch plug. Sprayed it with carb cleaner, blew it out with
compressed air, rinsed the fuel tank, cleaned the fuel filter. I thought
I'd have to get new fuel lines, but then I realized it was the same size
as the fuel line I had bought for the leaf blower! So, I checked for
compression with my finger, pulled the plug and checked for spark, put
the new hose in, put it back together. Started on the first pull.

I revved it up, all was good. But then when run at high speed it starts
to struggle, like it's not getting gas, then it quits. Put the choke
on give it a pull or two, and it starts right back up. And that is
what it was doing a decade ago when it wouldn't run! Doh! So now I'm
thinking it's likely the primer bulb. It seems to have a lot of air,
like 50% in it when it quits. Also, pumping the bulb, I can watch fuel
in the lines and it looks like it moves back and forth, instead of in
one direction. I'm thinking that it probably has a check valve in it
that's kaput and it's probably also leaking air. But there is no sign
of leaking any fuel. Being old, it should be replaced and I have one
on order. But in the meantime, some questions:

This bulb is separate from the carb. Do they typically have a check valve
in them? There was a little plastic widget in the fuel line, but on the
parts diagram it calls it a "connector" and from the size and shape, I
think that's all it is. I didn't use it, opting to just run one length
of fuel line instead. I think it's purpose is just that it's a bit easier
to put together with two pieces of line and then join them. But since
I don't have the new primer bulb, I'm thinking that I will get it fired
up, then remove the primer bulb and bypass it with that old connector.
I figure once it's full of fuel and good to go, it doesn't need the primer
and I can find out for sure if it is the primer without waiting for the
new one. Does that sound like it should work?




The check valve is in the carburetor if this is the typical Walbro
deal.

It's a ZAMA, China's finest.


That is the flat mylar piece under the big screw. It is not
unusual to see gas going both ways but more should be going in one
direction. You can usually buy the whole carb for a few bucks more
than the kit.

This is a fancier one, they call it quick start or something.
It has what amounts to a choke knob that's part of the carb that
connects to a red know that comes out of the house. To start it,
you twist that knob that works against a spring and locks. Once
it's started, first time you give it throttle, it automatically
releases the choke widget. The choke isn't the butterfly type either,
it works a valve inside the carb. Funny thing, according to the part
numbering, I see that same carb come up without the quick start gizmo
and with it. Without it, it's a $15 carb from China. With it, it's
a $35 carb.




Do you have the adjusting tool? Sometimes all you have to do is run
the screws in and out a little to dislodge something stuck in there,
Maybe remove the screw and blow it out, then readjust.

I don't have the tools and didn't remove those screws. You're right,
I said I cleaned it all out except for what was behind one welch plug,
but I didn't remove the those needle valves either. But, I don't think
it has anything to do with the problem. When it runs, it runs perfectly,
max RPM, goes like hell. But then after 20 secs to a minute it starves
out like it's not getting gas. I'm betting it;s that bulb. I found the
connector from the old hose, pulled it off, it's like I thought, just
that, essentially a nipple. I'm going to use that to bypass the bulb.

If I get to it. I just got a rope over a 3" tree limb that's 25+ ft in
the air. Now I have the rope saw and have to cut it off, back and forth
we go.....