On 2/5/2011 10:43 PM, Dean Hoffman wrote:
Taylor wrote:

My snow blower has a Briggs & Stratton 7.5 hp "Powerbuilt Snow"
horizontal engine. It has always need a little choke to run smoothly
after it warms up. With no choke it runs, but stumbles slightly. With
one click it is a bit smoother, and with two clicks it runs the
smoothest. More than that, there is too much choke and the engine will
die.

Thinking that perhaps something is clogged in the carburetor/jet, I
replaced the whole carb with a new one. The result is exactly the same.

I have fresh gas, use Sta-Bil, etc. I'm not overly worried about it, I
just use two clicks of choke for best power.

However, I suspect that I'm not getting the full 7.5 hp with the choke
restricting air intake. I'm also curious what the problem is. A
repairman said that all engines are tuned lean due to EPA rules. Of
course there is no way to adjust the mixture.

Any ideas what causes this? Is the repairman right about the mixture
set overly lean on purpose?

Thayne's suggestions about lack of fuel seem the most likely. Does it
have a fuel filter? On-off for the fuel? Have you tried running it with
the gas tank cap loose or off? Any chance of anything plugging the fuel
outlet of the fuel tank?

Because it is a snow blower, there is no air filter. The carburetor is
inside a "snow hood" which is designed to help it stay warm and prevent
icing. There is nothing that I can tell is plugging the fuel outlet,
and there is no shut off. I'll try running it with the gas cap off.

There are no adjustments on the carb either.

Thanks everyone!