On Monday, March 4, 2019 at 11:21:37 PM UTC-5, Clare Snyder wrote:
On Mon, 4 Mar 2019 19:21:21 -0800 (PST), wrote:

On Friday, March 19, 2010 at 6:26:07 PM UTC-7, deuce wrote:
I have a Honda EB3000C generator with a Honda GX200 motor. It's only
a couple of years old and has very low hours. I decided to drain the
fuel and refill with fresh fuel. It had sat for about a year. It
wouldn't start at first but I sprayed a shot of Gumout into the carb
bore and it started on the next pull. So I let it run for about 10
minutes and it ran beautifully. I decided to drain the carb so I
siphoned out must of the fuel in the tank, restarted the motor and
shut the fuel supply valve off. It ran for about three additional
minutes but instead of stumbling and dying like I expected it started
to backfire very loudly so I quickly turned it off. I thought maybe
some water had gotten into the fuel so I drained the sediment cup and
the carb bowl. I put some fresh fuel in the tank and tried to restart
it. It would start and run maybe 2 seconds, then backfire and die.
Thinking there still may be some water in the carb I redrained the
sediment cup and the carb bowl and tried to restart. Same thing, run,
backfire and die. I added a little Heet to the fuel, repeat drain and
restart - same thing. I'm thinking the original backfire episode may
have damaged something but before I tear into it further I thought I'd
solicit any experience anyone might have with a similar problem.
Thanks in advance.

did you ever get this fixed?
Lean backfire on shutdown is VERY common and totally normal,
particularly on a C.A.R.B. compliant motor.

But obviously failure to ever re-start and run again is not.....

It's an old and mostly irrelevant thread, but given the description
and symptoms, sounds like some gunk from old fuel has fouled the carb
or other part of the fuel system. The poster implied that it had old fuel in it.
The carb may need to be disassembled and cleaned, they have cheap rebuild
kits available for common engines for ~$10 or less. Or a new carb, there
are chinese aftermarket ones for common engines that work.