True the O2 sensor will not make the fuel pump cycle, but there is nothing in the EFI system that senses fuel pressure. The fuel pump cycling is a function of the ECU programming and calibration. It is just something the ECU does, not in anyway related to fuel rail pressure. When replacing the O2 sensor, be sure to check for ANY exhaust leak. Any air (O2) into the exhaust system makes the ECU think the engine is lean, then compensates by adding fuel. It will add fuel to the point of an additional 25% over base calibration, then sets code 34.