LS2 with working EVAP

[BoulderCharles]

I decided to keep the EVAP system on my LS2 swap to avoid the gas fumes in my garage. I thought I would share my experience in case others wanted to try the same thing. Overall, it was fairly simple.

 

I got my LS2 from a 2005 Pontiac GTO so I just went ahead and bought the following for a 2005 GTO:

 

• EVAP Purge Solenoid (relocated to the firewall)
• EVAP Vent Solenoid (inside the hatch area, where the Datsun charcoal canister was)
• Charcoal canister (mounted near the gas tank under the car)
• GM MAP sensor (for the fuel tank pressure)

 

Here’s how I put this together (if I missed something, feel free to let me know):

 

• I have a Tanks, Inc. fuel tank so I had one NPT vent fitting and a small vent on the fuel pump.
• I used the NPT vent fitting (with a tee) for the filler neck vent and the charcoal canister.
• The charcoal canister has an output for the EVAP vent and one to the motor. I just ran a fuel hose from the canister to the purge valve at the motor.
• At the motor, I used the GM purge solenoid, mounted at the firewall, then sent it to the throttle body.
• The tricky part was the fuel tank pressure sensor. In the 2005 GTO it is built into the fuel pump. I realized the tank pressure sensor uses the same 5V signal as a MAP sensor and guessed that the ECU wouldn’t know the difference, which worked out.
• I attached the MAP sensor to the fuel pump vent with a short peice of tubing.
• Wired everything up to the ECU.

 

I know it’s a bit of a “can I make this work” exercise but it is fun to know it can work.