2G AWD fuel tank - question about hoses

[99gst_racer]

In each picture, I need to know the purpose of the circled area, and where the hose runs.

Let me know if you guys know.

Thanks!!

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[wishihadatalon]

I was way wrong

 

[TSi999]

Hey man! That big one is for the filler neck IIRC, runs right next to the filler. The smaller one in the second picture is the filler shut off check valve for when the tank gets full of fuel!

 

[99gst_racer]

Hey man! That big one is for the filler neck IIRC, runs right next to the filler.

Upon further investigation, I have found that this is 100% correct. But do you know what it's purpose is?

The smaller one in the second picture is the filler shut off check valve for when the tank gets full of fuel!

I'm not sure about this. It looks like that smaller line (circled in red) connected to a hardline that ran all the way up tot he engine for something. I'm guessing to the charcoal canister or something else emissions related.

Any thoughts?

 

[DGajre777]

If the red one goes to the engine bay it has to be the charcoal canister hose.

 

[99gst_racer]

If the red one goes to the engine bay it has to be the charcoal canister hose.

Ok, cool. Should I just plug it or leave it "venting" at the rear of the car?

 

[CanadianTSi]

Leave it vented.

 

[DGajre777]

Ok, cool. Should I just plug it or leave it "venting" at the rear of the car?

I say plug it. You can either plug it at the rear of the car or plug it in the engine bay. In my 98 the charcoal canister was (since I removed it) under the driver side headlight, towards the wheel. There were also metal lines running towards the stock SMIC location, you can plug it anywhere in the engine bay.

On a side note, I got a vented fuel cap, the pressure that comes off with the vented cap when my fuel tank is empty is amazing.

Leave it vented.

Tyler, I'm curious - why do you suggest to leave it vented? It would freak me out to have a line with fuel fumes under my car.

 

[elfroggo]

I think you answered your own question. With that line plugged, pressure builds up in the fuel tank.

 

[DGajre777]

I think you answered your own question. With that line plugged, pressure builds up in the fuel tank.

...which can be relieved by a vented fuel cap. I was wondering if there was another reason that Tyler knows about that I don't.

 

[CanadianTSi]

Just to simply releave the Pressure, its not like there's going to be tons of fumes pouring out constantly.

I have mine vented right under the fuel filter and I never smelled gas once while under the hood working on the car.

 

[DGajre777]

I have mine vented right under the fuel filter and I never smelled gas once while under the hood working on the car.

You don't smell gas while working under the car because the charcoal canister stores fumes from the gas tank until the car reaches about 3000rpm when a valve opens to send them through the hose to the intake.

Maybe I'm paranoid, but I freaked out when I saw someone throw a cig out of their window when I drove behind them and have my line vented. Then I capped it and got a vented fuel cap and now I don't worry about it. To each his/her own, I guess...

 

[wishihadatalon]

You don't smell gas while working under the car because the charcoal canister stores fumes from the gas tank until the car reaches about 3000rpm when a valve opens to send them through the hose to the intake.

Maybe I'm paranoid, but I freaked out when I saw someone throw a cig out of their window when I drove behind them and have my line vented. Then I capped it and got a vented fuel cap and now I don't worry about it. To each his/her own, I guess...

Haha good point. That would wreck your day

 

[1gcrazy]

Haha good point. That would wreck your day

Man...i'd love to be there for the fireworks...

 

[oldman]

Mine is vented just like Tyler but if you have a vented cap then you should be OK. If you don't and you have the pressure relief hose plugged allowing pressure to build up in the tank, your fuel pressure will sky rocket, much like backed up turbo oil return due to excessive crankcase pressure. If you are affraid of venting fume catching fire, what would be the difference with a vented cap? Maybe I don't know how vented caps work.

 

[99gst_racer]

Thanks for the responses, guys. I'll just leave it vented at the rear.

 

[DGajre777]

If you are affraid of venting fume catching fire, what would be the difference with a vented cap? Maybe I don't know how vented caps work.

The vented cap stays closed and releases fumes from the tank before you put fuel in your car so the excessive pressure doesn't blow up in your face (has never happened to me). In my case, I used to leave the cap on the car until I almost ran out of gas, but I realized that opening and closing the fuel cap to relieve pressure every 50-60 miles or 1/4 tank helps. The only difference is that the vented cap keeps the system closed until you decide to vent it compared to the hose hanging out the bottom of the car to vent fumes above 3000RPMs. I hope this helps.

 

[CanadianTSi]

You don't smell gas while working under the car because the charcoal canister stores fumes from the gas tank until the car reaches about 3000rpm when a valve opens to send them through the hose to the intake.

I don't have a Charcoal Canister, therefore the Fumes are "always" venting.

 

[oldman]

Dee, I don't see a fuel pressure gauge in your profile, I would double check your fuel pressure and make sure the stock fpr isn't being overruned due to return deficiency, been in many threads in the past with AFPR (yes AFPR) overrun due to the vent hose being plugged. In fact if memory serves, Jim (FORMONTOYA) was one of those victims.

 

[DGajre777]

Dee, I don't see a fuel pressure gauge in your profile, I would double check your fuel pressure and make sure the stock fpr isn't being overruned due to return deficiency, been in many threads in the past with AFPR (yes AFPR) overrun due to the vent hose being plugged. In fact if memory serves, Jim (FORMONTOYA) was one of those victims.

Will the stock FPR over-run with the stock fuel pump due to the charcoal canister being capped?



CanadianTsi - Never mind, I had a brain fart. I forgot that removing the canister eliminates the 'above 3000RPM' venting.

 

[oldman]

Will the stock FPR over-run with the stock fuel pump due to the charcoal canister being capped?

Yes, it has nothing to do with the flow rate of the pump, it has everything to do with fuel not able to flow back to the tank freely due to excessive tank pressure.

 

[romeen]

Just to simply releave the Pressure, its not like there's going to be tons of fumes pouring out constantly.

I have mine vented right under the fuel filter and I never smelled gas once while under the hood working on the car.

Agreed, not to mention that the relatively slow release of the vapors will allow the free air to rapidly dilute the vapors as they are released. If the car is in motion and you are venting to the air the diffusion of the vapors will be so rapid that I imagine the chances of igniting them are so slim as to not be a concern.

Now if your car has been parked for several hours on a real hot day with no wind and somebody flicks their still burning cigarette under the car, well who knows.

With respect to venting there is well documented benefits but only speculation of possible dangers thay may or may not be valid. Conversely, not venting carries with it documented adverse effects.

Personally I'll keep mine vented.

 

[99gst_racer]

Yes, it has nothing to do with the flow rate of the pump, it has everything to do with fuel not able to flow back to the tank freely due to excessive tank pressure.

Another thing to keep in mind - when over-pressurizing the tank and "messing" with the return of fuel, that will also cause problems with the siphoning of fuel from the driver's side hump of the tank on 2G's. Definitely a no-no.

 

[oldman]

Another thing to keep in mind - when over-pressurizing the tank and "messing" with the return of fuel, that will also cause problems with the siphoning of fuel from the driver's side hump of the tank on 2G's. Definitely a no-no.

Only with AWD, funny I was just reading about this last night on NABR because one of our "know it all" new members here was insisting that 255 will not overrun a stock 2G FPR.

 

[DGajre777]

Yes, it has nothing to do with the flow rate of the pump, it has everything to do with fuel not able to flow back to the tank freely due to excessive tank pressure.

Interesting... thanks Oldman, I'll uncap my charcoal canister line.