Air leak in my vacuum pump

My vacuum pump its not working, I think that the air in filting, but I don’t know from where, what can I do to detect the problem?

First of all, what kind of pump is it? Does it have quick disconnects? A vacuum gauge? Do you have a pic we can look at? The easiest thing to check is that the female quick disconnect is screwed into the top of the cylinder tightly.

If you can disconnect the pump hose from the cylinder, does it continue to leak or does it hold the vacuum?