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: electronically controlled cooling system L-Jetronic fuel injection pump element of a distributor-type injection pump Pump-nozzle injection system II