Tick Coming Form Fuel Rail

Ok , i can hear a slight tick from the truck, pretty much all the time, but barely audible, but it bothers me, so i got out my automotive stethiscope and it seems like the slight ticking is coming from the fuel rail, is there a small valve in the fuel system close to the rail that would be opening and closing or something that would cause the ticking? I changed plugs, wires, filter, anything else, thanks guys!

I get the samething after it rains.

Normal, that is the injectors pulsing. BTW, in the future please post the year.

sorry , i am usually real thorough, 2002, 4.8, just typed real quick, i remember reading about yours when it rains, but mine is all the time, and i can hear a pulse, so im sure that is what it is, the injectors, i need to run some sea foam through it or something, thanks!