fig1 illustrates a fuel system 1000 including a tank 1010 , a pump 1020 , a filter 1030 , a pressure regulator 1040 , a fuel rail 1050 , at least one fuel injector 1060 , and an internal combustion engine 1070 . these components are interconnected by piping as will be described in greater detail below . the tank 1010 holds fuel . the pump 1020 is shown connected to an inside of the fuel tank 1010 . in other words , the pump 1020 can be secured to or retained to or supported by the inside of the fuel tank 1010 . however , the pump 1020 can also be connected on an exterior of the tank 1010 , or can be remotely connected with respect to the tank 1010 . the filter 1030 and the pressure regulator 1040 are shown connected inside the pump 1020 . however , the filter 1030 and the pressure regulator 1040 , either individually or an integral combination , can also be connected on the exterior of the pump 1020 , or can be connected remotely with respect to the pump 1020 . the tank 1010 , pump 1020 , filter 1030 , and pressure regulator 1040 can be coupled by piping such that the fuel 1012 can be filtered in the filter 1030 before entering the pump 1020 , or between the pump 1020 and the fuel rail 1050 . coupling thus refers to any connection permitting fluid communication . the pressure regulator 1040 can be coupled to a tap in piping between the pump 1020 and the filter 1030 , or between the filter 1030 and the fuel rail 1050 . fuel 1012 that is bled - off by the pressure regulator 1040 is returned to the pump 1020 . the fuel 1012 supplied to the fuel rail 1050 is supplied to each of the injector ( s ) 1060 , and subsequently supplied by the injector 1060 to the engine 1070 , e . g ., into individual combustion cylinders of the engine 1070 . fig2 illustrates a flow - through pressure regulator 10 according to a preferred embodiment . the flow - through pressure regulator 10 includes a housing 20 . the housing 20 is separated by a valve assembly 30 into a first chamber 40 and a second chamber 50 . the valve assembly 30 has a passage 60 that communicates the first chamber 40 with the second chamber 50 . the valve assembly 30 permits or inhibits flow through the passage 60 . a filter 80 is disposed in the flow path of the housing 20 . the housing 20 has an inlet 202 and an outlet 204 offset along a longitudinal axis a . the housing 20 can include a first cup - shaped member 206 and a second cup - shaped member 208 that are crimped together to form a unitary housing 20 with a hollow interior 211 . although the unitary housing 20 is formed by two joined members , it is to be understood that the unitary housing could be formed with multiple members integrated together , or alternatively , a monolithic member . furthermore , while the preferred embodiment of the housing 20 includes cup - shaped members , the housing 20 can include other geometries as well , such as tubular - shaped members . the inlet 202 of the housing 20 is located in the first cup - shaped member 206 , and the outlet 204 of the housing 20 is located in the second cup - shaped member 208 . the inlet 202 can be a plurality of inlet apertures 210 located in the first cup - shaped member 206 . the outlet 204 can be a port 212 disposed in the second cup - shaped member 208 . the first cup - shaped member 206 can include a first base 214 , a first lateral wall 218 extending in a first direction along the longitudinal axis a from the first base 214 , and a first flange 220 extending from the first lateral wall 218 in a direction substantially transverse to the longitudinal axis a . the second cup - shaped member 208 can include a second base 222 , a second lateral wall 224 extending in a second direction along the longitudinal axis a from the second base 222 , and a second flange 226 extending from the second lateral wall 224 in a direction substantially transverse to the longitudinal axis a . the valve assembly 30 includes a flexible divider 300 , which can be a diaphragm . the divider 300 is secured between the first flange 220 and the second flange 226 to separate the first chamber 40 and the second chamber 50 . the first flange 220 can be rolled over the circumferential edge of the second flange 226 and can be crimped to the second flange 226 to form the unitary housing 20 . in addition to the divider 300 , the valve assembly 30 includes a tubular member 320 and a closure member 340 . the tubular member 320 is located in a central aperture 306 of the divider 300 to provide the passage 60 . the tubular member 320 includes a first tubular portion 322 and a second tubular portion 324 . the first tubular portion 322 is disposed entirely within the first chamber 40 and has a diameter disposed along the axis . an upper surface of the first tubular portion 322 extends substantially transverse to the longitudinal axis a and contacts a lower operative surface of the divider 300 . the first tubular portion 322 forms a chamber 326 housing the closure member 340 . the second tubular portion 324 is disposed substantially within the second chamber 50 and has a diameter disposed along the axis . the diameter of the second tubular portion 324 is smaller than the diameter of the first tubular portion 322 . an outer surface of the second tubular portion 324 is secured to a spring retainer 302 , preferably by an interference fit . the outer surface of the second tubular portion 324 , however , may be secured to the spring retainer 302 by staking or crimping . a lower end of the second tubular portion 324 extends beyond the divider 300 into the first chamber 40 and forms a unitary tubular junction 348 with an upper end of the first tubular portion 322 . the second tubular portion 324 includes a plurality of tubular apertures 325 located in an end proximate the outlet 204 to provide a flow path through the passage 60 . the closure member 340 includes a ball 342 retained in a ball retainer 344 . the ball retainer 344 is disposed in the chamber 326 housing the closure member 340 and can be a flat annulus secured within chamber 326 by a flange provided at the lower end of the first tubular portion 322 . the flange of the lower end of the first tubular portion 322 allows for the ball retainer to move within the chamber 326 . this can be achieved by providing an aperture in the ball retainer 344 with an outside diameter which is smaller than an inner diameter of the first tubular portion 322 . the difference in diameters allows the ball retainer to move freely both axially and radially within the chamber 326 . the ball retainer 344 has a central aperture and a plurality of retainer apertures 346 located along a circumference of the ball retainer 344 . the central aperture of the ball retainer 344 is somewhat smaller than the diameter of the ball 342 and is finished to prevent a rough surface from contacting the ball 342 . the plurality of retainer apertures 346 in the ball retainer 344 permit flow through the first tubular portion 322 . an upper surface of the ball 342 seats on the tubular junction 348 . a lower surface of the ball 342 seats on a seating surface 230 formed in a center portion of the first base 214 along the longitudinal axis a and opposite the tubular junction 348 . a first biasing element 330 , which can be a spring , is disposed within an inner diameter of the second tubular portion 324 , substantially within the second chamber 50 . an outer surface of the first biasing element 330 contacts an inner diameter of the second tubular portion 324 . the first biasing element 330 extends along the length of the second tubular portion 324 . an upper end of the first biasing element 330 engages the end of the second tubular portion 324 proximate the outlet 204 , while a lower end of the first biasing element 330 contacts the upper surface of the ball 342 . the first biasing element 330 biases the ball 342 at a predetermined force toward the base 214 . a second biasing element 90 , which can be a spring , is disposed entirely within the second chamber 50 and is concentric with the first biasing element 330 . the second biasing element 90 engages a locator 228 on the base 222 of the second cup - shaped member 208 and biases the valve assembly 30 toward the base 214 of the first cup - shaped member 206 . the second biasing element 90 biases the valve assembly 30 at a predetermined force , which relates to the pressure desired for the regulator 10 . the base 222 of the second cup - shaped member 208 has a dimpled center portion that provides the outlet portion 212 in addition to the locator 228 . a first end of the second biasing element 90 is secured on the locator 228 , while a second end of the second biasing element 90 can be supported by the spring retainer 302 . the operation of the flow - through pressure regulator 10 will now be described . it is to be understood that the following description can also explain the operation of the invention when utilized as a pressure - relief device . the second biasing element 90 acts through the spring retainer 302 to bias the divider 300 , and hence the valve assembly 70 , toward the base 214 of the first cup - shaped member 206 . the first biasing element 330 biases the ball 342 of the closure member 340 , against the seating surface 230 in the base 214 of the first cup - shaped member 206 . when the ball 342 is seated against the tubular junction 348 , the valve assembly 70 is in a closed position , and no fuel can pass through the regulator 10 . fuel enters the regulator 10 through inlet apertures 210 and exerts pressure on the valve assembly 70 , including the divider 300 . when the pressure of the fuel is greater than the force exerted by the second biasing element 90 , the valve assembly 70 is displaced along the longitudinal axis a toward the outlet 204 . the force exerted by the first biasing element 330 unseats the ball 342 from the tubular junction 348 creating a pathway for the fuel . fuel enters the first tubular portion 322 around the ball 342 and through the plurality of retainer apertures 346 located in the ball retainer 344 . the fuel enters the passage 60 through the gap created by the unseated ball 342 and exits the passage 60 along and transverse to the longitudinal axis a through the plurality of tubular apertures 325 located in the end of the second tubular portion 324 proximate the outlet 204 . as the fuel pressure is reduced , the force of the second biasing element 90 overcomes the fuel pressure and returns the tubular junction 348 to seated engagement with the ball 342 , thus closing the passage 60 . operating in this manner , the regulator 10 is able to maintain constant fuel pressure in a fuel system . while the invention has been disclosed with reference to certain preferred embodiments , numerous modifications , alterations , and changes to the described embodiments are possible without departing from the sphere and scope of the invention , as defined in the appended claims and their equivalents thereof . accordingly , it is intended that the invention not be limited to the described embodiments , but that it have the full scope defined by the language of the following claims .