high-pressure fuel pump TSI (FSI) The following can be shown: How the inlet and outlet valves work. Up and down movement of the pump piston. How the pressure relief valve works. Fuel intake stroke, fuel recirculating, fuel pumping stroke. description ordernumber 500 see also: Common Rail Piezo-injector pressure-wave supercharger pump element of a distributor-type injection pump distributor pump (adjusting the injection timing advance)