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: roots blower L-Jetronic fuel injection air-flow sensor with fuel distributor K-Jetronic solenoid valve of a radial-piston distributor pump