For the M3, it has a main pump and a pre-pump. The primary purpose of changing the fuel line block-off clamps is to stop the fuel leakage while replacing a main pump. Then you remove the cover of electric connections that lead to the wires to be disconnected from the pumps. At last, unscrew all those nuts that hold both fuel pump and its assembly them-selves. As well as disconnecting hose from the pump then take it out of bracket, uninstalling old pump and installing new one entails putting this in bracket, connecting hoses and attaching pump with its bracket to auto whereas attach hoses as well as electrical connections then remove those block off clamps that have been placed on fuel lines and electrical connector too. Finally replace the cover and insulating sheet; install rear seat cushion then reconnect negative cable for battery before checking ordinary operation together with fuel leakage presence. As regards E36 models, their level sensors are connected to or attached at their tanks such that pumps are found there also. One way is by testing for 12 volts at relay socket for a pump prior jumping terminals for examining current flow through its circuitry among other ways listed below like via using an amp meter while others include by checking fuel pressure using gauge.Installation of necessary parts or change should occur when any problem is realized here.