Engine shuts down when o cap is off

[Fordfan74]

When starting the car while running runs fine then when removing the oil cap the car will shut down replaced the pvc valve any other ideas what it could be

 

[lwarrior1016]

Opening the oil cap introduces a vacuum leak to the crankcase. It makes sense that it dies (in my head it makes sense anyway).

 

[dameion50]

Make sure the hose running from the filler neck on the valve cover to the intake isn’t torn or broken. Normally having a vacuum leak would make it idle high, not make it die. Maybe pull the hose I mentioned and cap off the port on the intake pipe and then try it.

 

[lwarrior1016]

Make sure the hose running from the filler neck on the valve cover to the intake isn’t torn or broken. Normally having a vacuum leak would make it idle high, not make it die. Maybe pull the hose I mentioned and cap off the port on the intake pipe and then try it.

If I pull the vacuum hose off my 5.4l f250, the truck runs real rough and then dies.