MonteHall

on my 98.
looks like it's going to the fuel regulator.
I noticed newer vette's don't have it.

what is it?
is it important?
and what happens if I broke it?

in this pic, I've outlined it in red (and the regualtor, I think) , then filled it in in grey (it would be behind the fuel rail cover, though)

97C5ENVY

It's a vaccuum line for the fuel pressure regulator.

MonteHall

is it important?
I broke (plastic part snapped in the middle) mine, but the car seems to run just fine.

white90conv

If it goes to the throttle body, not the air bridge, then it probably is a vacuum line. On the C4, this adjusts the fuel flow when the manifold vacuum is high.

dpd

without that line hooked up to the pressure regulator,you are running at head pressure[full fuel pressure],if you don't fix it you will be fouling plugs soon because your running too fat[rich]

MonteHall

so just some plain vacuum hose should do the trick?

I've been told that since I have a Blackwing, the vacuum line needs to be moved... any truth to that?

dpd

you want to get vacuum line that is resistent to gas/oil vapors.as far as having to move the hose,i don't see or understand the reasoning to that theory,but i don't run a blackwing.the blackwing is south of the throttle housing,so i don't see the effect.

MonteHall

something about there not being enough restriction to get a good vacuum.
sounds like a load of bull to me, but you never know.

dpd

sounds like .vacuum is created after the throttle blade.

MonteHall

I am confused.
if I follow the air, then the pressure regulator hose is before the TB (in the accordian hose) not after.
so there is no vacuum there?

dpd

are you sure?wouldn't make sense but i could be wrong.there is no vacuum in the accordian.air before the blade is atmospheric[positive pressure]

MonteHall

yep. if you look at the pic, it goes in at the bottem the accordian piece, just before the TB
I'll see if I can find a better pic

SteveDoten

you won't see it if your car is '99 or newer, the 97-8's have a supply/return fuel system w/ the fuel regulator on the rail, the 99 newer cars moved the reg. into the fuel filter, the said vacuum line is only on the 97-8 cars

dpd

i agree,the 99-early 03's have the regulator in the filter and ffs[late 03 to now]have 2 regulators[primary/secondary]in the tanks.i just don't get how the earlier cars operate the regulator with the line in the accordian.unless the regulator works backwards.never heard of it,but it doesn't mean it's not possible.

Dan_the_C5_Man

Who said there is "no" vacuum in the accordion? You will find some level of vacuum all the way to the front of the filter element.

runman

that hose does nothing more than allow the fuel pressure regulator venting to atmosphere. Fuel pressure is constant, several other engines use that design

dpd

i had a brain fart.my fault.

97C5ENVY

It's a vacuum line trust me. Part number #12557155 - ~$17.50 (GM List)

Rhode Warrior

It's called a fuel evaporative line.

LoneStarFRC

97C5ENVY is correct.

TUBE, FUEL PRESS REG VAC 97-98 Y (LS1) 12557155

I think you may have looked at:

TUBE, EVAP EMIS 97-98 Y (LS1) 12552222
CNSTR PURGE (FROM
VALVE TO THROTTLEBODY)