on a 1998 chevy monte carlio i have a problem the engine start but cut off and i chech the fuel line coming from the pump and the pump pumping fuel but low pressure is this mean the pump is bad?
Vacuum leak or your window is open.
If it it shutting off because of the hissing, it is likely moisture getting at electronic parts and shorting them. The hissing would be caused by cold water contacting hot engine parts. If the hissing is only heard after YOU shut off the car, it is likely a small leak in a vacuum hose. These are usually easily fixed.
remove headlight switch
Could be a "hissing" sound
The hissing may be due to a disconnected vacuum line. Look for a loose vacuum hose and/or a tube on/near the throttle where it might connect to.
Some systems use engine vacuum to move the control doors. You could have a vacuum leak.
On a Dodge truck, the vacuum switch is on the transfer case.On a Dodge truck, the vacuum switch is on the transfer case.
It is probably a lack of vacuum to the actuator that controls the air doors. Check for hissing noises under the dash and make sure all vacuum lines uinder the hood are connected and not kinked.
sounds to me like it has a bad vacuum leak, check around the intake for hissing sounds
Vacuum hose leaking.
Exhaust leak? Vacuum leak?
I am not a corvette mechanic, but I call BS on vacuum diagnostic switch.