Vacuum hiss after engine switch off

[Vp4ever]

Hi all,

I've known of a vacuum leak for a while. Tracking it down has been the problem.

Today after reversing out to check the radiator & switching off I can hear a hiss coming from the top rear of the engine.
The hiss stops when the fuel pump shuts down about a minute after ignition off.

A vac hose to/from the the vac switch that controls the purge canister? Or a fuel line somewhere back there?
Anyone seen or heard this & done it before?


Also, how long should the fuel pump run on after shutdown? It seems to go on for a couple of minutes. Would the leak have something to do with that?
My understanding is the fuel pump is controlled by 2 switches. 1 thru the ignition & 1 thru an oil pressure switch so the engine must be turning & ignition on for fuel to flow in case of a prang. Correct?

 

[Not_An_Abba_Fan]

The fuel pump should shut off as soon as you turn the engine off.

I'd be looking at the fuel regulator for your vacuum noise, it also may cause the pump to run on for a bit.

 

[delcowizzid]

the pump will run till oil pressure drops sometimes on good engines on a quick cold start they will continue running for some time its normal

 

[Vp4ever]

More checks today.
Heater/ac all working ok so I don't think it's that line.
Changed the short line from intake to purge valve. Not it.
Fuel lines to the fuel reg look ok.
Could it be the brake booster line? Seems very sloppy fit. & has those crappy hose clips.