1.  Field of the Invention
The present invention relates to a fuel pump of a vehicle, in more detail, a technology for reducing noise of a fuel pump disposed in a fuel tank storing liquid-state LPG (Liquefied Petroleum Gas) and improving durability. 
2.  Description of Related Art
Vehicles using LPG as fuel are equipped with a fuel tank storing liquid-state LGP, and particularly, in LPI (Liquefied Petroleum Injection) vehicles, a fuel pump that pumps up liquid-state LPG itself and sending it to an injector is disposed in a fuel tank. 
FIG.  1 shows an example when a fuel pump which is used in LPI vehicles is mounted in a fuel tank in the related art.  A pumping unit 500 of the fuel pump is sunk in liquid-state LPG a mounting unit 504 that fixes the pumping unit 500 with respect to the fuel tank 502 and is connected with the outside of the fuel tank 502 is fixed to the fuel tank 502, and a vent tube 508 that is connected with a space through which lubricant for lubrication of pumping unit 500 flows, a vent channel 510 and a vent hole 506 of mounting unit 504 which are connected with vent tube 508 are provided. 
Vent hole 506 opens the space, through which the lubricant flows is, to the inside of fuel tank 502 such that the internal pressure of fuel tank 502 is exerted, in order to manage changes in temperature and pressure due to operation of the fuel pump, in which liquid-state fuel should not flow into vent hole 506. 
As exemplified in FIG.  1, however, when liquid fuel flows into vent hole 506, the lubricant and the liquid fuel are mixed and the fuel mixed with the liquid fuel is evaporated and removed with the evaporation of the liquid fuel, such that pumping unit 500 is worn by reduction of the lubricant and noise is generated from pumping unit 500, thereby reducing durability. 
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.