Small Engines (Lawn Mowers, etc.): Craftsman 4hp snowblower stalls under load, throttle plate, throttle lever

Question
Snowblower is about 7 years old and wasn't used for about 2 years.  I bought a new Tecumseh carb from Sears and installed it.  I read some of the other questions you answered regarding setting the idle and high speed screws and I think I have it setup properly but not sure because I do not have an idle position on my throttle lever it is either between fast or slow or off.  I also realized there was probably a trace of 2+ year old gas still inside it that should have been completely drained and could have clogged the brand new carb.

It will start OK and seems to run fine.  When I engage the auger it stutters a bit but when the engine is warmed up I can see it adjusts itself to full throttle to keep the engine running when auger is engaged and will reduce the throttle after the auger gets going for a few seconds.  But it will completely stall when trying to use it under even the smallest load of snow.

Not sure if this is normal .. When starting I place the throttle lever at full and it indeed moves the throttle plate to full throttle but once it gets started the throttle plate moves itslef to about half throttle when idling with the the lever still at full throttle.  When I engage the auger the throttle plate moves itself to full throttle to be able to keep the engine running.  What I am not sure about is if the throttle plate should be staying at full throttle constantly unless I actually adjust the lever manually.

In summary .. it stalls under load and I am not sure if the throttle is working properly.  Also wanted to verify how I should be setting my throttle lever when adjusting the mixture screws.

Thanks in advance for your help.  

Answer
The throttle will appear almost closed when not under load.  When you engage the auger the governor should initially open the throtle plate then it will back off a little.

I'm assuming you have two mixture needles. The high speed needle will control most of the carb in you particular machine since it does not have a low speed.

Are the needles marked?
If so, try turning the high needle out just a little.

Since the machine is as little old you may want to check the muffler to make sure there isn't excessive carbon build up; this will cause poor performance under load.

Let me know about the carb and the muffler/exhaust port.
Eric