This is s good start:
Here are some videos that may help you. Sometimes the male connector is not all the way in, and you will experience that the gauge on your "gun" (link to picture) will go up with no added vacuum pressure into the penis pump cylinder. The reason for this is because the valve in the, MityVac -...
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This is for both air and water: check the hose connections between the cylinder, water trap, and the gun. Do not test the line going from the water trap, through the hose, and the pump gun by submerging them in the water. The other parts are line, such as the cylinder, the line, and the cylinder side that does not go towards the trigger pump gun. Most of the probable leak when using the water trap is the large o-ring in the water trap unit. Make sure it's not kinked, missing, or damaged.
For the line leak from the water trap to the pumg gun, disconnect the hose at the water trap that connects to the cylinder, put your finger and seal the barb for the water trap, and pump. See if there's leak somewhere between the sealing cap for the water trap or around the barbs for the water trap and the trigger pump gun.
If you're not using water, do the same test above after following the direction from our brother SIM's video, then do the pressure test without the cylinder.
Bathmate device doesn't mean you have to use a bath tub. I use my Bathmate out of the shower all the time. Same with the MityVac. It's how well you prevent water from spilling all over the place is the key to not making your normal bed into a water bed. Most of my pumping done on my bed.