Micky wrote:
On Thu, 26 Nov 2015 19:04:46 -0600, Unquestionably Confused
wrote:

On 11/26/2015 4:15 PM, Micky wrote:

I was happy when I started to take the spark plug out and it was
loose I could do it with my fingers, but, after checking the gap,
putting it in tight didn't make it start any better.

Still, the engine on the 50cc motorscooter has started many times
now, but it never runs more than 30 or 45 seconds.

It starts even if no ether is used, often fairly quickly (5-8
seconds with the electric starter), if it's been 10 minutes or more
since the last time I ran it or tried to run it.

But after 15 seconds it dies.

It runs pretty fast if I give it a lot of throttle, but it still
starts to die within 15 seconds. Sometimes if I had it running
fast, it lopes along very slowly for another 10 seconds, instead of
dying more quickly. If I try to start it immediately after it's
died, I don't think it's ever started then.

Removing the gas cap didn't help (it wasn't on tight in the first
place because I have no key and have to use a screwdriver if I put
it on tight. And I'm sure it's not air-tight even when perfect.)

It couldn't be bad gas or it wouldn't start at all.

I've removed the spark plug and the gap turned oout to be good,
0.7mm, and it sparks every time, when I electric crank it with the
plug out of the engine.

The owner's manual talks about not starting but not about starting
and dying. I'll go look at the manual

I think it's a fuel problem. It's certainly not compression and I'm
99% sure it's not spark.

Almost certainly a fuel DELIVERY problem. I occasionally (which is
why I haven't torn it down or taken it to the shop to have it done)
have a very similar problem with a ZTR mower with a 22HP engine.
Will start right up then, within 15-20 seconds, will die off and
won't start again. Replaced the filter, then the fuel pump, all to
no avail.

Finally, before calling for help, I pulled the fuel line from the
output of the fuel pump to the carb and tried blowing into it. No
luck but I

OKay, I tried that today.

wasn't sure if it was plugged or if I merely lacked the lung power to
get the job doneg

I once blew hard to blow something up and I felt one of Eustachian
tubes swell in my head, or at least that's what it felt like. Scared
me, the thought of it bursting in my head. So I don't blow that hard
anymore.

Grabbed a 60cc syringe with a catheter tip

Okay, I didn't have 60 but I found a 20cc syringe, still in its
sealed, sterile, paper wrapper. I've had it in my junkbox for maybe
20 years, don't remember where I got it. This was the day I was
saving it for!!

that fit nicely into the fuel line

Well it was too small, but it had an opening-cover that was bigger so
I cut the tip off of that and put the hose on it.

and tried blowing INTO the carb. Again, no luck. Changed tactics

No luck.

and tried sucking OUT from the carb and it worked. After doing so I

Pulling slowly did nothing, so I quickly pulled the plunger straight
out of the rest of it. After 3 or 4 times, I saw a trace of something
in the hose. Did it 10 more times and the trace got longer,
eventually a bit of gas was coming out almost an inch, and then
receding again.

could pump into or suck out of the carb. Something in there
blocking or stuck. Reattached the fuel line to the pump, turned the
key and I was in business. Didn't have that problem for at least
five or six weeks - after a spell of temperature swings and little
use. This time my first step was to try and draw fuel from the
carburetor and again I was successful on the first try.

Give it a whirl; what do you have to lose?

So I was psyched, and when I started the scooter right afterwards, it
seemed to run faster (with more throttle) and a longer, but it was
only a few seconds longer at most and then it loped and then it
stalled.

Debated whether to drain the tank and buy a gallon of hi-test, and
then it started to rain, earlier than predicted. It's going to be
colder or rainy for a week.

The milky brown gas is probably water in the gas. Maybe the top layer
is gasoline and it floats, but after 30 seconds it uses that and the
rest comes from the bottom of the tank which has more water, then
after 10 munutes somehow there is gasoline in the bowl t hat floats to
the top of the bowl and it works again. Makes no sense.

But I think I have to drain the tank, remove the carb and turn it
upsided down to pour everything out.

Unless there's some way I could empty the bowl without removing the
carb? Blowing air through it from a little compressor? How long
would that take?


(One poster said he couldn't take the carb apart without drilling out
the rivets.)

Any gas that is cloudy, green, or dirty looking ought to have been disposed of
from day 1.
Trying to fix an engine full of bad gas is a waste of time.

Chances are the carb is cruded up and jets may be plugged and the float valve is
very likely plugged. Just blowing air into the carb may pop out metal plugs
internally that can be removed to clean passages, but you want to do it
carefully so you know where the plugs go. The plugs I've seen were round dome
shaped sheet metal.

Do you get good gas flow out of the fuel lie when disconnected from the carb?