Outdoor Power Equipment and Small Engines - 10 hp craftsman stalls under load

I bought a used 10hp craftsman snowblower before last season. It was a little difficult to start and stalled once it encountered snow. I took the carb apart and rebuilt it, and now it starts easily, but it still stalls under load. (we had about 1" of snow this morning, so I scraped together a pile to test it.) I can hear a noticeable drop in RPM's when I put it into high gear, even without the auger engaged. Belts seem fine, no broken shear bolts. I think its a problem with the governor mechanism. Is there a way to diagnose this? I called sears service this weekend and asked if there was a way for them to check how the machine runs under load without snow and they said 'not really', so I don't want a service call and have them tell me that it starts fine and runs well, when it'll stall with the first flake again. Is the governor mechanism something that is easily serviceable? I have a Tecumseh service manual, but it doesnt' go into much detail on the governor. Any help would be appreciated.

Since I can't hear the engine firsthand I could never tell you if you have an internal governor issue. What I can recommend is making sure the static adjustment (external) is proper. Your service manual you have should be Tecumseh part number 740049 and in section 4, page 27 you will find the static adjustment procedure. Do this first and be sure all the governor and throttle pivot points are free in operation, especially at the speed control bracket and at the throttle shaft in the carburetor body.

Something that I do and seems to work well is the following. After rebuilding carb and setting high speed adjustment at 1 1/2 turns out, start and run engine for 5 minutes to get warm. Place blocks or anything else under machine to elevate wheels. Engage wheels and secure lever with something ( I use cable ties) Then engage auger and secure that lever. The engine is now operating at load, although not the same as snow but better than no load. Now adjust high speed needle with throttle open full by turning to the left until it sputters and then to the right until it sputters then back to the midway point. Hopefully this helps

I pulled the spark plug and checked it and it had a lot of carbon on it. I checked the numbers and it didn't match what the manual called for. I got the correct one and now the engine sounds like it is running much stronger, and without the drop in RPM's. If the previous owner had installed too cool of a plug, would that be enough to produce such a lack of power as to stall in minimal snow? I don't want to be caught with a stalled snowblower once it starts to fly.

At our shop, we use champion J19LM or equivalent on the Tecumseh 4 cycle engines in the snow blowers. Sounds like the old plug was on its way out. Hot plugs help if the engine is using oil or bad fuel to prevent fouling and most engine manufacturers have gone from the old Champion J8 to the J19LM.