Loss of pumping pressure

I rigged up my own pump, having pump a pump with a gauge from Harbor Freight. The problem is, I can’t keep it from gradually losing pressure. Does anyone else have this problem? I create a great seal, and I slowly pump up to between 4-5”hg. After a few seconds, the gauge starts to slip down. I have disconnected the hose from the cylinder, and stuck my finger on the end of the hose and pumped…..same thing happens. Could it be the pump? Is this normal?

What kind of cylinder do you have?

Is the female quick disconnect screwed securely into the top of the cylinder? I wrap the threads of this fitting with teflon tape for a leak proof seal.

Have you shaved the base of your shaft?

Like I said, it’s not the cylinder or where the hose connects to the cylinder. I disconnect the hose from the cylinder, and put my finger on the of the hose, and then I pump it. The pressure obviously jumps up more quickly in a case like this, but it too loses pressure. Yes, I have shaved the base of my shaft and the cylinder is a modified acquarium gravel cleaner, but it’s tight.

Lick your thumb and then hold it over the male pump fitting. Once squeeze puts me up to about 8”hg and it holds pretty well. When my thumb is dry, the pressure bleeds out slowly.

I will give that a try tonight when I’m home.

Maybe you’re expanding faster than you manage to pump….

It’s the pump. If I wet my finger and just put it on the tip of the pump, it still loses pressure. I have to figure this out, or take it back for a new one. It’s less than a week old.

Sounds like a bad pump. Just to make sure the air is still not escaping from your finger print grooves, put a piece of plastic wrap or aluminum foil between your finger tip and the pump nozzle. If you can’t make it hold pressure, exchange it.