We hooked up our pneumatic system to a cylinder following the basic setup.
Our pump gauge only read until 75psi. The pump also was still on and didnt shut off. I think the switch kicks in at about 115 psi to shut the pump off. anybody else had problems getting the air tanks to reach 115psi? We checked all of our hoses and their was no apparent leak.
Also, can you adjust the switch to shut off the tank at 75psi? If so, how? is it done through the code?
check your fittings all around with a little soapy water. Or pump up the system with a pressure gauge attached, turn the pump off, and watch the pressure - you should not be able to see the needle on the gauge move in less than a minute or two.
I would try disconnecting the entire circuit after your pressure gage and pressure switch. Once you have done this plug the open end. If you are using tubing, a t-fitting with two ends connected with a single loop of tube works well as a plug.
Try your compressor using this setup. This will help determine whether your problem is a leak or actually with the compressor.
For instance, if the pressure goes up to 120 in this situation, you would know that you had a leak somewhere. If the pressure still stops at 75 psi then you need to start looking at your compressor.
There are a few things that could be wrong. Although the pump works in either polarity, it is more efficient and will run cooler when running in the correct direction. It is possible that the wiring feeding the compressor has a loose crimp or that you have a defective breaker which will supply less current to the compressor. The compressor has a pressure relief valve that is designed to pop open at 125-130 PSI that may be damaged and leaking. It is the brass fitting connected to the head of the compressor. Finally, screw fittings should be assembled with Teflon tape (available at any hardware store) to help seal the connection. 90% of the problems with pneumatics are leaks. If you system is already assembled with valves in place, clamp the tubing as it exits the storage tanks and see if the compressor will reach full 120 PSI. Valves sometimes leak especially when installed backwards.