TwoOlives

AHA!!!  Fixed!!!...First thank you all for getting my brain into gear, considering all your helpful comments, and putting my feet on the right path.   About 5 a.m. this morning, while trying to grab another hour of sleep, thinking about your various advisements, a flash of inspiration occurred.  The one thing that I never mentioned because I thought it was insignificant...and the one thing out of the ordinary...was tipping the machine forward to get to the bottom pannel.  I began to wonder what if the float hung up?  Initially, it was suggested that I check the gas system.  I checked the tank, and the fuel line--but not the carb.  So, this morning, i decided to remove the carburetor and inspect the float.  After all, it ran fine after the belts broke, but not after I replaced the belts...so something happened in between.  BUT, before i did that i downloaded: http://www.cpdonline.com/692509.pdf

Glad I decided to read about the carb and its parts before I took a wrench to it...a lot of little things in there, and a warning to replace the gasket once the bowl has been separated from the carb.  Hmmmm...and then in one diagram, I saw the "screw."  And then my memory kicked in.  When I tipped the machine forward I was worried about gas spillage.  I put a sheet of saran wrap over the tank opening and screwed the cap down...and then, I pushed and turned the "screw" a little because I thought it was how you bleed the fuel bowl--I wanted to empty all the gas!  Well, guess what?  It isn't a fuel bleeder, but rather a "main adjustment screw" which meters the flow of gas into the carb.  And I did turn it...maybe a couple of times because the spring on it rotated and I wasn't sure if it was turning; or maybe it didn't need turning but pushing.  Anyway, I did disturb its original setting.

I played with it this morning and found the "sweet spot."  The engine runs well; the drive is now clear.  And, as my reward, its snowing again.

Thank you one and all again.

Also, the ignition is all the way in.  And I never had to separate the front and back halves of the engine.

Shryp:

I had about a 1/4 tank when i encountered the brick.  And I filled it to about 3/4's of a tank after the belt change.

I changed the oil, gapped the plug, and filled the tank before the first snow.  I ran it successfully for three snowfalls.

To change the belts with this machine, probably others as well, you tip it forward and rest it on the mouth of the auger housing, and remove a six bolt panel on its bottom.  I found it an easier belt change if I taped the auger drive handle down.  This lifted the support bracket and allowed tight, but easier access to the belts.  I don't recall dislodging anything, but I'll take another look.

I lowered the machine back to its usual standing position, the back end never crashed down.

I can understand how a vacuum would interefere with the gas flow.  I'll loosen the cap and see if that does anything.

Thank you for your quick responses:

borat, jrtrebor,Shryp, and carib:

The machine was bought new about four years ago.  I would expect the shear bolts to be new and part of the original equipment, but ya never really know for sure.  I'll check them out.

The brick was hit about two weeks ago.

The engine never died, but the auger quit immediately as the brick was wedged into the auger's discs.

I drove the machine up to the barn under its own power, it never balked, backfired, or made any sound other than usual.

After I installed the new belts and cranked it up, I didn't hear any backfiring. 

It has an electric start and per the instructions I did not prime it.  The engine started after a couple of cranks.

It pounded a bit until I adjusted the choke and then it ran pretty much as usual.

Snow shot out of the chute as it progressed along the drive for about 60 feet.  Then the engine died.

I used the pull starter about five times to get it going.  It would start each time, after a couple of pulls, but it would die in less than a minute.  I ended up pushing it to the barn.

I've got a Yardman 644E, 8hp/24".  I ate a brick which stopped the auger, the shear bolts did not shear, two auger drive belts snapped.  I've replaced the belts, but had a difficult time starting the engine.  It ran for about ten minutes and the snow flew out of the shoot, so I'm thinking that part is repaired, but the engine putters to a stop after a few minutes.  It was running great prior to the brick.  I was hoping for a quick fix--gas line maybe?  So I changed the gas and checked the fuel line.  Looks okay to me.  But, the engine isn't doing well at all.  Timing?