referring now to fig1 the fuel filling pipe system inlet housing is shown generally at 10 . housing 10 includes a threaded fuel cap receiving portion 12 which has an annular mounting flange 14 used to secure the inlet housing to the vehicle . the annular flange is preferably provided with a plurality of mounting holes for receiving the appropriate fasteners for securing the housing to the vehicle . surrounding mounting holes 16 , the flange is formed with reduced strength sections 18 which are designed to break away during a crash , thereby permitting the inlet housing to be severed from the automotive vehicle . fig2 also illustrates these reduced strength sections on mounting flange 14 . while three equally spaced reduced strength sections and three equally spaced mounting holes 16 have been illustrated , it will be understood that a different number and arrangement of mounting holes and reduced strength sections may be utilized without departing from the spirit of the invention . inlet housing 10 also includes an intermediate housing portion 20 which is slidably received within the annular hub portion 22 of cap receiving portion 12 . hub portion 22 is formed with an internally stepped diameter 24 , and intermediate housing 20 is formed with a corresponding externally stepped diameter 26 which carries a rubber or plastic o - ring seal 28 . the o - ring seal 28 deforms between the annular hub portion 22 and the intermediate housing portion 20 when the intermediate housing portion is inserted into the hub portion . the o - ring seal thus prevents fuel within the interior of the intermediate housing portion from leaking to the outside . hub portion 22 is also provided with a plurality of windows 30 which receive retaining lugs 32 formed about the outer periphery of the intermediate housing portion 20 . lugs 32 have ramped leading edges and stepped trailing edges so that the lugs snap into windows 30 in a simple snap together assembly procedure . once snapped together , the stepped trailing edges of lugs 32 prevent the intermediate housing portion from being pulled out from within hub portion 22 . intermediate housing portion defines an outer vent chamber 34 and a vent cut - off chamber 36 . between the outer vent chamber and the vent cut - off chamber , a splash door mounting component 38 is disposed . the splash door mounting component is slidably and internally received within intermediate housing portion 20 , and housing portion 20 includes a plurality of raised lugs 40 which confront and retain splash door mounting component 38 . the splash door mounting component includes a pair of spaced apart flanges 42 which carry one end of a spring steel splash door 44 . the opposite end of splash door 44 is unsupported and is free to deflect out of the way when the gas pump nozzle is inserted . splash door mounting component 38 defines a first aperture 46 which is sized to receive a gas pump filling nozzle . for automotive vehicles which require unleaded fuels , the aperture 46 should be of sufficiently small diameter to prevent insertion of the comparatively larger nozzle used to dispense leaded fuels . thus a leaded fuel nozzle will be unable to enter aperture 46 to deflect splash door 44 . with splash door 44 remaining in the normally closed position , it completely blocks aperture 46 , thus preventing the introduction of leaded fuels into the gas tank . splash door mounting component also defines a second aperture 48 , which serves as an air bleed port . the intermediate housing portion 20 has a distal end configuration ( shown generally at 50 ) which includes a male barbed nipple portion 52 for connection to the fuel hose 54 , and a second male barbed nipple portion 56 for connection to the vent hose 58 . hoses 54 and 58 are depicted in fig2 . the nipple portions 52 and 56 preferably have a plurality of longitudinally arranged , annular barbs for force fit retention of the fuel hose 54 and vent hose 58 . within the interior of the fuel hose nipple 52 a plurality of nozzle depth stops 60 are arranged . these depth stops are arranged generally as shown in fig1 and serve to check or stop the inserted end of the gas pump nozzle at the proper position for filling , and also prevents over insertion of the nozzle to the point where the nozzle handle might scratch the vehicle &# 39 ; s paint job . vent nipple 56 defines a vent passageway which communicates with vent cut - off chamber 36 , and similarly , fuel hose nipple 52 defines a fuel passageway 64 which likewise communicates with vent cut - off chamber 36 via an intermediate fuel passageway 66 . the intermediate fuel passageway is defined in part by a nozzle guide member 68 which has inwardly tapered sidewalls to direct and center the nozzle , when inserted within the intermediate passageway . the intermediate passageway further includes a nozzle end seal 70 disposed adjacent the nozzle guide member and is spaced from the stops 60 by an annular bushing element 71 . the nozzle end seal has an annular protuberance which is inclined or swept backwardly toward the nipple 52 . nozzle end seal 70 is preferably of an elastomeric material and is adapted for tightly gripping the end of the gas pump nozzle , to isolate the open end of the nozzle from the vent cut - off chamber . such isolation provides an important advantage of permitting the fuel to be dispensed at high flow rates without the risk of the vent passageway 62 becoming blocked by the backflow of fuel . this also insures that the automatic cut - off mechanism of the gas pump filling nozzle will not be erroneously triggered . further , seal 70 insures that fuel pumping pressures do not leak into chamber 36 , but rather act with full force to operate the fuel tank check valve mechanisms , yet to be discussed . referring now to fig2 vent hose 58 and fuel hose 54 are shown in their attached positions . both hoses are provided with snap fitting connectors 72 and 73 , used to connect the hoses to the fuel tank , yet to be discussed . in order to prevent the build - up of static electricity which can result from the rapid in - rush of essentially non - conductive fuel through fuel hose 54 , the fuel hose is fabricated to include an electrically conductive , or at least partially conductive ( between 10 - 5 to 10 - 4 ohms / cm 2 ). this may be accomplished by forming a coextrusion of an outer hose layer 74 and an inner layer 76 . the inner layer 76 may be fabricated from a very thin layer of plastic that has been coated with or imbedded with a graphite material or another conductive material . in the alternative , hose 54 may be a single wall extrusion with an internal coating of a conductive material . connectors 72 and 73 may be fabricated of metal or plastic . if desired , the ends of hoses 54 and 58 may be expanded to make a friction fit sealing connection with the quick connector fittings on the gas tank wall , yet to be discussed . a suitable connector and quick connector fitting is disclosed in u . s . patent application ser . no . 360 , 201 , filed mar . 22 , 1982 and entitled &# 34 ; a swivelable quick connector assembly &# 34 ;, which application is now u . s . pat . no . 4 , 601 , 497 a continuation - in - part of u . s . patent application ser . no . 201 , 711 , filed oct . 29 , 1980 now u . s . pat . no . 4 , 423 , 892 . referring now to fig3 the gas tank wall is shown in cross - section at 78 . gas tank wall 78 is provided with a fuel hose fitting 80 and a vent hose fitting 82 for receiving connectors 73 and 72 , respectively . both fittings incorporate check valves which are biased to normally seal both the vent passage and the fuel passage . the check valve of the fuel hose fitting 80 , when acted upon by incoming fuel pressures , moves against the spring bias force to a position which permits fuel to enter the tank . the check valve of the vent hose fitting operates in the opposite direction to permit pressurized air and vapors displaced by the incoming fuel to escape . more specifically , both fuel hose fittings comprise a nipple forming body portion 84 which encloses bias spring 86 , valve body 88 and rubber o - ring seal 90 . the body portion 84 provides a valve seat against which valve body 84 and o - ring seal 90 seat . preferably , bias springs 86 provide sufficient force to prevent the weight of fuel within the tank from opening the vent hose fitting valve during a collision or roll - over situation . thus , even if one or both of the hoses 54 and 58 have been punctured or disconnected , fuel will not escape from the tank . the pressure required to open the check valve within vent hose fitting 82 is generated by the incoming fuel pressure , which at normal flow rates will exceed the vent hose capability , thereby creating a positive trapped air pressure within the tank . this trapped air pressure builds up until the force of the bias spring is overcome , whereupon the air pressure is vented through vent hose 58 . body portion 84 is preferably formed with an outwardly extending rebent portion 92 which serves to capture the body portion within the corresponding opening in the tank wall . preferably this rebent portion is formed to capture an annular gasket 94 against the tank wall . the body portion and gasket are held in place by a force fitted retainer 96 which is preferably formed of metal and provides a spring force which bites into or grips the body portion 84 . the retainer is formed with a flanged skirt 98 which maintains the assembled relationship of the body portion and gasket with the tank wall . the opposite end of retainer 96 is formed with an outwardly presenting annular or partially annular bead 100 which snap fits with the associated connector 72 or 73 , to hold the connector tightly in place while permitting the connection to swivel . although the various components of the invention may be fabricated from a wide range of materials , the presently preferred embodiment utilizes fuel resistent plastic injection molded parts except as otherwise indicated . suitable plastic materials include polyethylenes , polyesters , nylons , and so forth . gaskets and seals may be fabricated of rubber or other elastomeric plastic materials such as polyurethane or the like . nozzle end seal 70 , for example , may be manufactured from rubber or polyurethane . except as otherwise noted , fuel hose fitting 80 and vent hose fitting 82 are preferably fabricated of metal , although plastic materials might also be utilized . connectors 72 and 73 are likewise preferably fabricated of metal , although plastic may be utilized , in which case it may be preferable to flare the ends of hoses 54 and 58 somewhat , so that they will fit over the nipple ends of the fittings 80 and 82 . in operation , the spring steel splash door 44 is held in a normally closed position , wherein the door 44 acts as a &# 34 ; backsplash &# 34 ; element to cause leaded fuel from a large diameter nozzle inserted into the chamber 34 to splash back and cause the nozzle to shut off . likewise , both check valves within the fuel hose fitting and vent hose fitting are also held closed , which prevents the escape of fuel and fuel vapors , although permits the release of overpressures may develop in the gas tank . when filling the tank , the gas pump nozzle is inserted through aperture 46 , deflecting splash door 44 , and thence through intermediate fuel passage 66 until the end of the nozzle stops against depth stops 60 . the nozzle end seal 70 grips the end of the nozzle , so that fuel cannot splash back into the vent cut - off chamber and also so that pumping pressures are directed through the fuel hose and not into the vent cut - off chamber 36 . fuel may be pumped at comparatively high flow rates under pressure of the gas pump . the gas pump pressure overcomes the bias spring of the check valve within the fuel hose fitting , thus allowing fuel to flow into the gas tank . the incoming fuel displaces the air within the tank so that a positive trapped air pressure builds up within the tank . this causes the check valve within the vent hose fitting to open , whereupon the displaced air is vented into vent cut - off chamber 36 and out through aperture 48 . by providing an escape route for back pressures which is isolated from the gas pump nozzle by means of seal 70 , the automatic cut - off mechanism within the gas pump nozzle will not be falsely triggered by the back pressures . this allows the gas pump to be pressure filled at the maximum flow rate of the gas pump . the invention thus eliminates the annoying pretriggering of the automatic cut - off mechanism and thereby allows the gas tank to be filled to its maximum capacity quickly and without having to repeatedly reset the cut - off mechanism by repeatedly squeezing the fuel dispensing handle . in an alternative embodiment , useful in jurisdictions with stringent air pollution regulations , the vent hose 58 may be provided with a t - fitting as illustrated in phantom lines as fitting 102 . t - fitting 102 may be coupled to a vapor collection cannister 104 which traps fuel vapors before venting to atmosphere so that fuel vapors expelled from the gas tank will be diverted into cannister 104 instead of being allowed to escape to the atmosphere . in such an embodiment , the second aperture 48 would be permanently blocked or omitted , and a suitable nozzle engaging seal similar to seal 70 would be provided around the aperture 46 or within the cap receiving portion 12 , so that the majority of the vapors expelled from the gas tank will be routed to the vapor collection cannister due to the comparatively higher pressure within the vent cut - off chamber 36 . once the gas tank is completely full , however , raw fuel will fow out through the vent hose fitting thereby blocking the opening to the cannister 104 . when this occurs , back pressures developed within the fuel hose will be sufficient to trigger the cut - off mechanism . while certain representative embodiments and details have been shown for the purpose of illustrating the invention , it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit or scope of the invention as set forth in the following claims .