Leakage at the vacuum line is not the only indicator of a bad FPR. I just worked on a truck that had the fuel pressure falling off to nothing as soon as the pump shut off. I tried pinching off the return line and it held pressure. A quick regulator swap and it was fine. It never did show any sign of fuel in the vacuum line. It would certainly be a good idea to get a fuel pressure gauge on it so you know exactly where it's at with the engine on and off.