Every time I turn off my truck, I get this strange noise from under the hood. Sounds like pressure bleeding off through a diaphram of some sort. Takes about 10-15 seconds to complete.

Is this normal? Maybe my fuel pressure regulator going bad?

 

Was the A/C on?

 

Nope. Don't use the A/C. Someone suggested that it could be the power booster / check valve.

I'm gonna pull the vacuum hose on the power booster today if the rain will stop, and see if it still makes that "bleeding" noise.

 

Could be a leaking purge canister. They hold vacuum indefinitely between engine operations. Well they are supposed to.

 

Ok, I found it. It's the EVR. It's really pretty loud, especially with the hood up.

When I turn off the truck and pull the vacuum line that goes to the EGR valve, the EVR quits making noise. If I put that line back on quickly, it starts making noise again...apparently until all the vacuum bleeds off.

Does that mean the EVR is going (or already is) bad?