That will probably take some kind of in line specialty vacuum guage if you are trying to test the fuel system. you can try to completely seal something over the gas tank fill hole and see if it get sucked on to it, something thin and pliable so you can see a concave to it if there's a suction. But it would need a good seal and it wont be as quick as cheking the air inlet.
aslo the fuel pump causes the suction and the pressure in the lines so it may be the pump itself. If there was a hole in the line you'd see fuel leaking somewhere. Idk if a snow mobile has a positive displacement fuel pump or not or if it has some kind of return line. Or if the carburator is electronically controlled or mechanically metered. To be honest there's a whole bunch of things that could be wrong with the fuel system, best bet is to see a mechanic if you have no idea what you are looking at. Honestly i have no idea about snow mobiles or carburated systems, im a heavy equipment diesel mechanic.
The best way to check compression with no gauge is to remove the spark in each cylinder and hold your finger over the hole and turn the engine over if you have good compression it will suck on your finger if not you could have a valve stuck open or bad compression rings.It could also be out of time if the fly wheel key is sheared Hope this helps