No problem.
Pumps creating pressure, after you placed the pump you have to adjust the pressure the pump should generate, for that use (HEAT) for more pressure, or (COOL) for less, or use (PROP) to select a pressure.
The selected pressure is displayed at the HUD as the Heat of the pump, positive means pressure, negative means suction.
But be careful, some of the materials are very sensitive to pressure, and/or pressure changes.