I have a 2004 Passat TDI. My son has been driving it and now it won't crank, I've replaced the fuel filter but when I turn the key on no fuel comes out of the supply line. I hear a little noise at the pump but just for about 2 or 3 seconds. The only fuel that came out came was from the "out" line off of the fuel filter and it was black, almost like it had dissolved something made of black rubber, another description is, it looked "sooty." Shouldn't I have enough pressure (with the fuel supply line feeding into a cup) to fill a plastic cup within a few seconds when I turn the key to the "on" position? Because I get nothing, zero, zilch, nada. Any advice would be helpful, thanks.