It likely goes back to the carburetor. Was the fuel added new and clean? If so maybe there was debris in the tank or line that the shop did not clean out. There is another possibility that the fuel cap isn't venting. If you remove the cap momentarily- will the machine start and run well for a while?

Is the gas reasonably fresh and in a clean container?

tomplum & canguy

Thank you for taking the time to read and respond to my message.

It was fresh gas when I brought it to the shop and it was stored in a clean container. Do you have a suggestion of how I can clean out the fuel tank? I suspect the repair shop had to drain the tank to replace the fuel line and shut-off valve.

I'll try loosening the fuel cap and see how the machine runs. It always stalled when there was a load on the machine. I don't recall seeing a vent hole in the cap however, there is a silver colored concave disk on the underside of the cap. Is that there to prevent the fuel from leaking out of the vent hole that I haven't seem yet?

I read somewhere that the gasket between the carb and engine could be damaged or the carb has loosened up.

It's just odd that it stalls suddenly...no sputtering, struggles to stay running or warning, it's immediate.

I just hope that it's not July by the time I figure this out.

Thanks again

Many of these vent through the threads in the cap- so no hole. If the choke helps it continue running- then it is a good bet it is starving for fuel. If the cap thing doesn't work out- there just may be a bit of water/ debris in the bottom of the carb bowl. You may want to contact the shop to see if they will have another look if it's been a short time.

This one's a little off the wall, but it worked for me.
Between snow storms, I blew an empeller bearing. So I broke the machine down and while waiting for the bearing, I decided to address a few other issues; I noticed an oil leak coming from one of the head bolts- so I pulled the tank. Checking the head bolts, I noticed that they loosened to 10-12 foot pounds. Being the metric equilivant of 5/16, I re-torqued to 20 foot pounds and viola! Problem solved! This is my story, GOOD LUCK!!

I've had similar symptoms about 5 times in the 20 years I've owned my 624. Tunes out the carburetor screws back out with vibration causing it to run super lean. One time they were so loose, I was surprised it ran at all!

Not sure this is your issue since you recently had it services but I figured I'd post anyway for those who may experience this.