White smoke when vac line is unplugged

[CudderNation]

I've been having trouble finding a cause for white smoke to come out of my car that smells just like gas. I was checking if my fuel pressure was right and when I undid the vac line on the FPR and it caused white smoke to continuously come out, it is a Megan Racing FPR could it be bad or?

I just know that undoing the vac line causes to the fuel pressure to rise but not sure about the concept behind it so don't know what is bad to cause he smoke.

Thanks for all and any help!

David Phung