Fuel System Noise?

Cracked radiator tank turned into a leaking intake manifold which then morphed into new regulator and injectors on my 02 4.3 Xtreme (long story; don't get me started!).

Everything's back together and running fine, but now I have a weird high pitch whine coming off the distibution block where the fuel inlet and return lines connect to.

The new design has the inectors right at the ports, so the only thing really going on here is the fuel pressure regulator.

Only makes the sound when running. If you press on the wiring harness on top, or twist it a little, the whine changes pitch, but does not completely go away.

No other issues, and runs fine; anybody have any idea what this could be?

The only noise that could possibly be generated in the plenum, is fuel going through the fuel pressure regulator and fuel lines. If fuel pressure and leakdown are within spec, I wouldn't worry about it.

Thinking it may be a vacuum leak, where the large O ring may have rolled as I put on the top of the intake manifold....changing it out this weekend and I'll let you know what happens.

Thanks for the reply, OM!

I suppose that's a possibility however, it would have to be a very small leak, maybe too small to make any noticeable noise. If that's the case, the PCM would most likely detect it, turn the SES light on and set DTC P1128 in memory for "unmetered air". If you lube the O ring with motor oil before installing the plenum, it greatly reduces the possiblity of rolling the O ring. Might be worth checking. Post what you find.

Update.....

Replaced the upper intake gaskets, and the noise didn't go away. Contacted Sorenson directly, and their reply, directly from their email, is:

"The whine may be a vacuum leak coming from the main injector body where the wiring harness is. This is caused by the lack of sealing where the injector terminals poke through the body. If the noise is objectionable, you may return the entire unit as defective."

So, we don't seal it, sometimes it leaks, and if you don't like the noise we'll send you another one which may or may not leak.

Putting in new unit; 50/50 chance the noise goes away, so wish me luck!