inline fuel filter with check valve?? - The 1947 - Present Jun 23, 2010yeah check valve would solve nothing// i'd do a complete tune up and adjustment of all ignitioin and fuel system b4 blindly throwing parts at it// a very over looked item is the in carb fuel filter in quadrajet carbs, as well as petrified air filters causeing air starvation to engine,cleaning setting gaps on both points and plugs Q-Jet Check Valve Fuel Filter Application? | K5 BLAZER NETWORK Sep 01, 2006AC GF470 or WIX 33051 = short paper in carb filter with check valve. AC GF471 or WIX 33052 = long paper in carb filter with check valve. I read in a GM book,that the real reason for the "check valve" is to "prevent fuel loss out of the carb in a rollover accident"!!. THAT is supposed to help is beyond me!.