You have a broken or blocked aspirator, Chiliuno.
If water is coming out the suction aperture, then there's probably not a clear path for the water to travel. My aspirator spits water out the suction pipe if there's anything stuck in the internal nozzle.
If you can, dismantle the unit and inspect it for corrosion buildup or anything stuck in there. there may be a twisted baffle inside the aspirator which makes the water jet out in a spiral fashion, so don't confuse this with something that shouldn't be there.
Aspirators can be quite useful though, especially when you need a high volume vacuum pump, or when stripping solvents and corrosives that will eventually destroy up a mechnical pump, so fixing your aspirator before getting another pump might be a good idea.
I can also recommend buying a jet pump and making a recirculating aspirator station, because the pressure doesn't vary as wildly as that of your municipal water supply.
TFSE yields a great many discussions in what to look for in a mechanical vacuum pump when you do decide to splash out for one. Edwards and Ritchie are the two brands I most frequently remember reading about here, but it really doesn't matter what brand you buy provided it has the correct specifications.