Fuel Rail/Fumes Leak

[DND]

I've got a 2.0L turbo motor from a 2003 WRX, what is the third connector on the fuel rail under the return line for?
What, if anything, is supposed to be connected there?
I don't see a third connector in the build manual picture on page 207, or any reference to one, but I've got one and I'm not sure what it is for.

The reason I ask is something popped loose a week ago Thursday that resulted in fumes coming into the cabin when driving/applying throttle (but not so much at idle) and I haven't been able to figure out what that is yet. I think all the lines in/out of the tank are secure and I don't tend to smell gas fumes when the car has just been sitting and not running.

[Bob_n_Cincy]

I've got a 2.0L turbo motor from a 2003 WRX, what is the third connector on the fuel rail under the return line for?
What, if anything, is supposed to be connected there?
I don't see a third connector in the build manual picture on page 207, or any reference to one, but I've got one and I'm not sure what it is for.
The reason I ask is something popped loose a week ago Thursday that resulted in fumes coming into the cabin when driving/applying throttle (but not so much at idle) and I haven't been able to figure out what that is yet. I think all the lines in/out of the tank are secure and I don't tend to smell gas fumes when the car has just been sitting and not running.

DND
The 3rd port near the fuel lines is a vacuum line for the gas tank EVAP system. Most builders have completely removed the EVAP system and capped off the vacuum ports on the intake manifold. I think a few have kept the system if their state required emission testing.
Bob

evap.jpg

[DND]

I've been reading the various threads on the forum about using charcoal canisters and I'm planning to add one to see if that solves my fuel smell issue.
I've got a couple more questions now though:
1) Do I need the solenoids in the factory system?
2) Should I vent the canister to atmosphere or feed it back into that evap vacuum line?
3) Would either of these Mazda canisters work instead of the GM one recommended on old forum threads?
https://www.ebay.com/itm/BRAND-NEW-O...8/361339135644
https://www.ebay.com/itm/99-05-NB-MA...R/153092208754

[STiPWRD]

I capped off all my evap related hoses coming off the engine and removed the solenoids. I'm running the vent hose from the fuel tank to a yamaha scooter charcoal canister that vents to atmosphere. I don't get any fuel smell with this setup. To answer your questions:

1. No
2. Vent to atmosphere. I wouldn't feed fuel vapor back into the engine unless you were absolutely certain of what you were doing.
3. Probably

[DND]

Thank-you, I will do that.
Other than that third line at the fuel rail where else do I need to check to make sure things are capped off?

[STiPWRD]

There is a barb (~10mm) that comes off the intake manifold that normally provides vacuum for the brake booster, make sure that's capped. In general, I would check around the intake manifold for any open barbs or hoses. There are also breather hoses that come off the valve covers and top of the block that are used by the PCV system. The turbo inlet tube has a bunch of hoses that also provide vacuum for things (boost control solenoid, etc.). You'll probably notice if something is uncapped and causing an issue.