Penis pump keeps depressurizing

Hi, I don’t know what I do wrong but my penis pump keeps lowering the pressure rapidly. I need to pump it like 2 seconds after I stopped pumping to regain what is lost. I shaved my penis and I use rubber on the base of my PP to minimize the pressure lose, but still it is pretty frustrating. Can someone give me some advice, how to stop this thing from happening?

What kind of cylinder are you using?

Idk, what do you mean by kind of cylinder. It has 3 cm radius, made of plastic.

Share a picture of what it looks like.

Is your pump separate from the cylinder, i.e., is the pump connected to the cylinder with a hose? If so, check your hose connections. Remove the hose from the pump, place your finger on the pump fitting to create a seal. Pump up and see if the pressure holds. If not, the pump has an internal leak. Add the hose, then repeat the process with your finger against the open hose end.

Most of my cylinders are solid, with the only openings at the base and for the hose connection, but one has a screw on top which has a gauge in it. The o ring began leaking so I had to replace it.