02 s10 won't hold fuel pressure ?

I have a 02 s10 4.3 v6 and my prob is when the truck sits either overnight or for a few hours it takes forever to start I checked the service port for the fuel and its got no pressure at all after sitting and if I hold the key to run position before starting for a few seconds it'll build up pressure and when I crank it starts right up my ques where would this check valve gadget that keeps pressure in the line be located I know they stll the fuel pump parts only as a whole. Which comes with all this plastic crap for $500 and I aint got that kind of money to spend is there a universal valve I can add in along the fuel line right at the pump or is it built into the pump itself I'd rather just fix this valve since the guage unit its built into works fine