Here is my 4th gen tank that I modded to get rid of all the EVAP stuff. It would be same mods for any car that you want to put a 4th gen tank in w/o the EVAP. Let me know what you guys think. I researched a lot about venting it "the right way". Ill try it later this week to see if it fills up without any problems. I got rid of the EVAP to avoid running unessecary crap inside the engine the compartiment and outside too. Helps with the diet too! Thanks to MrDude_1 who helped me with this.

Question.

I've got a thirdgen tank and I think my evap isn't working correctly, probably because I hooked the line from the tank directly to the sensor/switch on the side of the throttle body and removed the coal canister completely.

Is this something I can do to make it so my filler cap doesn't blow out a ton of air when I open it?

(On a side note, my brand new fuel pump makes a ton of noise until I get on the gas, I'm think its cause the tank is under too much positive pressure?)

I've got a thread going on LS1 tech with all the info, just not sure what the fix is.

Good question Steven, Ive never really looked into the 3rd gen EVAP system, but what you did sounds ok. (Canister delete).

Sounds like your tank is under positive pressure like you mentioned. Since you are using the 3rd gen tank, the only thing venting it is the vent check valve thing (white ball thing), which should open when the tank reach an internal pressure of about 8psi. Maybe yours is faulty.

To check if its ok, remove it from the rubber line and put air thru it. I used compressed air from my air compressor that I setted @ 8psi. The valve opened right away to let the air out. If you dont have access to a compressor, just remove it and drive around with it removed, see if the pump is quieter and theres less air coming out of the gas cap.

Thanks for the advice. There is the line going from the hard line for the Coal can straight to the plastic sensor/(maybe switch) that sits next to the fuel rail, then goes into the throttle body.

I was going to pull the line off before it hits that 4th gen part and see if that helps (also cap the TB to keep from having a vacuum leak) After I do that I'll check the white thirdgen part to see if it is working as well.

Sounds good man, keep me posted.

Is that the purge solenoid for the evap?

I'm thinking so. But does the 4th gen tank have some sort of extra sensor to tell it when to open?

I figured a 4th gen didnt come with a Coal Canister, so I removed it.

They do come with a coal can. Its mounted right on the tank tho. ECM controls the vent noid.

And that vent noid is on the tank itself or is that the plastic part that sits on the plenum next to the fuel rails?

Vent solenoid is on the tank too. What sits on the intake is the purge.

Ok, so I spoke to Rex @ hawks, he said on his swaps he is going a thirdgen tank, the walbro pump, then he takes the third hard line for the EVAP to the thirdgen coal canister, then runs the rubber tube to the plastic peice to the TB.

So looks like I have to go find a coal canister since I threw mine away

I tried hooking up my tank this way and it doesn't work. I even replaced the check valve thing with a new one from GM. It won't let me put gas in the tank.

Has anyone got it to work the way that it is in the pic?

I'm just going to put the 4th gen charcoal canister back on and give it a try that way.

I'm almost thinking the air filter and the white vent thing in the pic should be switched.

Why in the world are you guys adding this stuff back.
Mine's been offf since day 1. Only 1 single line running to the front.
Makes life easier and the install cleaner.

The white thing is a pressure relieve valve, not a vent valve.

I was planning on keeping the 4th gen charcoal can on the tank, but not running the purge line to the engine. What I've gathered is the PCM needs the fuel level input in order to properly run the purge, and you can't run a fuel gauge off the fuel level sensor and send it to the PCM without a 4th gen instrument cluster (which I have no desire to do).

Reports are if you keep everything on the tank, and leave the purge line open at the tank, everything functions.

Guess I'll find out when I actually get far enough down the road to actually put gas in the tank.

I got gas to go into my tank by taking off the huge vacuum cap shown in the above pic. Its a 1/2 or 5/8". I just let all the outlets vent to the atmosphere. It made the car smell like gas when I was cruising around saturday night, I had a sore throat the next morning from the amount of gas I breathed in.

I'm adding the charcoal canister back in because I read somewhere that if you have a backfire in your intake and if you just have a line going from the intake to the tank then its possible the backfire can go back to the tank and cause an explosion. It might be a huge myth but I don't want to risk it. And I can't have it venting into the atmosphere because its too gassy. I'll also be running the LT1 purge solenoid which is located next to the LT1 intake since I'm running an LT1 engine.

Put the charcoal can back in and leave it piped as stock and it works perfectly. No fumes, no smell, vents the filler pipe safely, alllll goood. For any other swappers of LS1 tanks just leave the piping and the charcoal can in place and install the tank. Works A1 and its good for the environment and your health ( see sore throat comments above )

Has anyone figured out the venting other than leaving the EVAP components in tact? I don't think that this is an option for me.

Thanks,
Tony