Fuel Pressure solenoid, need a yay or nay

[Afroclipse]

At the end of the solenoid is a capped end, I can feel and here that its letting out air. I wanted to know whether that black cap is supposed to be on there to let air out or not, I know its the other seems obvious but I wanted to make sure capping it with something else wouldn't cause issues, I even blew into the cap to make sure it was capped and I almost blew up my cheeks.

 

[pneumo]

Yes, the capped end is supposed to be open to atmosphere. It's supposed to vent the line that goes to the FPR. It's not supposed to let air leak out from the hose that goes to the intake mani, so if there's air coming out of the FPR solenoid cap during a boost leak test, switch the 2 hoses around.

Or just bypass the solenoid and deal with hot start issues.