On Monday, October 22, 2018 at 5:00:27 PM UTC-4, trader_4 wrote:
On Monday, October 22, 2018 at 4:32:59 PM UTC-4, trader_4 wrote:
On Monday, October 22, 2018 at 1:40:40 PM UTC-4, trader_4 wrote:

OK, so here's the latest. Upon looking at the plumbing, I realized
that the primer bulb, even if it's leaking, can't be the problem.
It's on the after side of the carb. Fuel flows from the tank,
to the carb, out the carb, to the primer bulb suctions side, out
the primer bulb and back to the tank via the return line.

But, just to be sure, I did bypass it and the symptoms don't change.
Starts right up idles, runs up as you give it throttle, but at speed
after about 15 seconds, it just dies out. Further suspecting a fuel
problem, I tried running it with the return hose disconnected.
While it's running, no gas is coming out of the return. So, logically
what's happening, it's barely getting enough gas to run and when I
advance the throttle, there isn't enough so it quits. This is the
same problem it had ten years ago, when I gave up on it.

So, the only remaining two possibilites a

1 - The carb isn't pumping properly

2 - The fuel filter in the tank is clogged.


The fuel filter, I had out. It had a kind of red, oily look to it, I
presume from the remaining gas evaporating over ten years and the oil
and some residue being left behind. I sprayed it out with carb cleaner,
blew it out with compressed air and it looks OK from what I can tell.
I doubt that's the problem, but it's still possible that it's partially
clogged and can't flow enough. I will diagnose further.

The carb, IDK. Taking it apart it looked OK, a little residue that came
right out, no corrosion. I'm no ace with regular carbs, let alone these
two stroke gizmos. It has two plastic gaskets, one on each side. I
guess one or both vibrate to pump the fuel? One has a dime size dome
to it of the same material, no metal. The one on the other side has a
nickel size piece of
metal in the middle. IDK how flexible they are supposed to be, if they
can stretch and no longer work, etc. All I know is there isn't any
cracking, no missing pieces, they look OK, so what's wrong?

Here is a link to a rebuild kit on Ebay. The two plastic diaphragm gizmos
in mine are the two on the left side of the first/main photo. The other
similar ones are for other models. I guess I can
buy a rebuild kit. All the other pieces in mine, eg the valve, spring, etc
in that kit in mine look OK. Is there anything I should look for in those
two parts that indicate they are bad and the source of my problem?

Another question, on welch plugs, I remember on a Tecumseh, the service
manual said that after you put them in you should coat them with nail polish.
I did that. Seemed kind of nuts, like you'd think gas would dissolve it,
no? What are you supposed to do with welch plugs after you replace them?

I guess another option is just shell out $35 for a whole new carb.

TIA for any help.

To update one more time, I tried using the prime bulb to pump fuel.
It seems to do a lot of sloshing back and forth, which leads me to
believe there is a bad check valve, either in the bulb or carb, IDK
where it is. But it does pump some, and I tried to imitate a check
valve by using a pair of plier to clamp off the hose to the carb
while I depress the bulb, then take the pliers off, let it suck fuel.
There is always air in the line coming from the carb and no air in
the supply line from the tank to the carb. So, I think we can rule
out a filter issue, that wouldn't put air in there. The lines are
all new, so the only thing left is somehow air is getting in inside
the carb. But maybe that's normal, but I wouldn't think so. Plus
with the real problem being fuel starvation, it's consistent with
the problem being the fuel pump in the carb.

So, all the part arrived. New primer bulb, fuel hose, carb rebuild kit.
Put it all together and it's working! Seems like it might need a little
adjusting to run perfectly, but it's running fine enough that I used it
with the edging attachment to edge the lawn at the curb.

For what it's worth, the only difference in the new carb components vs
the old was that the thin plastic sheet that forms the valves and the
pump diaphragm is flat, tight. The old one had a bump where the
diaphragm is, apparently stretched from use. My guess is that was what
the problem was, that kept it from pumping enough gas. Worth remembering
if you take apart one, to know what to look for. I couldn't find anything
online where they said what a good one should look like vs a bad one.