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

Grabbed a 60cc syringe with a catheter tip that fit nicely into the fuel
line and tried blowing INTO the carb. Again, no luck. Changed tactics
and tried sucking OUT from the carb and it worked. After doing so I
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?

I'll give it a try.

I also went out in the dark and looked again for the fuel filter. It
wasn't in the tank, I'm glad to say, but it was hidden by a frame
member so I didn't see it. Only a little bigger than the last
section of my thumb.

So I'll try that too.