99 Squeak Under Dash

I have two annoying noises that both started recently on my 99 K1500 Suburban. The first is a vacuum-type hissing noise that can only be heard inside the vehicle at idle. It sounds like it's coming from the driver's side under the dash, but it has been elusive. I've spent an hour trying to find it with no luck. It doesn't do it all the time, and it goes away when I give it gas. I would describe it as a whistling type noise, though not high pitched, more of a whooshing sound.

The second one is a squeak that only happens when I push the accelerator with the engine running. I say that because it doesn't do it when I push the accelerator with the engine off. It's not the pedal or the cable -- I've ruled those out. It doesn't do it at idle, only when the engine rpm's run up above idle. This is a typical squeaking sound, but I can't figure out what would be moving in tandem with the engine revving up on the interior of the vehicle.

These two noises may be unrelated, but they are suspiciously similar, not in sound, but that one goes away when the other starts. Are there any type of vacuum-operated devices in the cabin of a 99 Suburban that sound like may be at the root of this?

I have two annoying noises that both started recently on my 99 K1500 Suburban. The first is a vacuum-type hissing noise that can only be heard inside the vehicle at idle. It sounds like it's coming from the driver's side under the dash, but it has been elusive. I've spent an hour trying to find it with no luck. It doesn't do it all the time, and it goes away when I give it gas. I would describe it as a whistling type noise, though not high pitched, more of a whooshing sound.

Hello RSmith,

I have the same problem/noise. I have tried to track it down with no luck. I also posted on another thread with same problem.

If you or any others have found/fixed this problem, please call.

Thanks,

Bob 940-902-1266

what is needed is the body style old or new ...1999 was transition year ..

Hello,

It's a '99. Annoying noise from under dash ; sounds like it's coming from flywheel area, but cannot be heard outside the vehicle. My guess,it's a vacuum leak of some sort.

Thanks,

Bob

Hello,

It's a '99. Annoying noise from under dash ; sounds like it's coming from flywheel area, but cannot be heard outside the vehicle. My guess,it's a vacuum leak of some sort.

Thanks,

Bob

you must give vehicle details ...eng/drivetrain old or new body style. etc...

Mine turned out to be the fuel pressure regulator. Strange that it sounded like it was under the dash, but it was. The fuel pressure regulator is within the upper intake manifold but somehow the sound travels, probably via the fuel lines.