What does the vacuum line off of the fuel pressure regulator do?

I am in the proccess of changing my intake manifold over to an aebs one and I noticed on my original manifold that I had the vacuum line capped off. It ran fine like this for 2 and a half years so im wondering if i should just leave it capped? or run it to one of the ports on the back of the manifold?

 

run it to one of the ports on the back of the mani, if its capped the pressure wont increase with increase in vacuum it will stay the same all the time, hook it up and you will see, look at a fuel pressure guage and rev the motor when you are looking at it and it will fluctuate depending on the vac the motor has at the time. you should really hook it up. also is this a b16?, if it is a 1st gen you will need a new style 99 si fuel rail to fit the aebs mani

 

You need to run it to one of the ports. You'll also need another rail as stated. If your vacuum line was capped off then under a load (WOT) your pressure would fall off, I would think at least. It would stay steady at idle and looes when needed.

 

i think its the other way around, hes running rich the whole time, i think the vaccum leans it out at idle, and as vaccum dissapears it restricts and rasies fuel pressure

so if you hooked it back up you probably could get another couple MPG back

 

Interesting, i guess ill hook it up.

The weird thing is that it ran great the whole time not connected to anything, i put like 40k on my b16 with it like that.

I already picked up the obd-1 fuel rail by the way.

 

yeah the back of the AEBS has like 4 ports choose one

 

I also put on a type R throttle body when I did the intake manifold and it has the map sensor on the TB. My car has one on the firewall.

From what i understand from searching i can run either map sensor? correct?

Also Can i just disconnect the Evap Purge solenoid? I read a thread that said i could with no negative consequences.