'97 c1500 5.7 bucks under any acceleration and now won't start. Fuel pressure reads slightly high at 72psi, should be 60-66. Fuel pump also runs constant with key on engine off. Removed the upper intake manifold to check fuel pressure regulator and noticed a small amount of fuel puddled in the manifold. Can't tell where it came from. With the key on I can hear a hiss and cant tell where in the manifold its coming from. Any ideas? I can't see the fpr leaking and don't want to throw parts at it that won't fix the problem.

 

Did a leak down test today. Drops from 70+ down to 30psi immediately after turning key off. Then slowly drains down from there. Pinched the return line and supply line in separate tests with the same results. Was going to replace the fuel pressure regulator but from what I read it isn't bad. Any help would be greatly appreciated.