A Diesel Fuel Lift Pump simply transfers fuel into the injection system from the tank. This fuel will not need to be highly pressurized, since that is what the injection pump is for, but it must be able to support the injection pump’s volume demands, which rely on the diesel fuel for lubrication.
Electric fuel pumps which were designed for gasoline engines are typically the lowest cost way to do this, and are typically mounted on the frame rail, close to the fuel tank. There are also more expensive, higher-end systems which usually come with filters and a way to suck the air out of fuel. This kind of system is usually very expensive, and sometimes very noisy, but they do bring excellent performance and unmatched reliability to the table.
