So I’ve used the search function, and none of the threads seem to have a definite answer. As of right now my canister hardline is just open in the engine bay. I understand that the only drawback to this is the possibility of smelling gas fumes and that it’s arguably safe to leave open. I don’t need to pass emissions standards of any type, but i believe I have a large amount of fumes I am smelling from it. I also understand stock set up is canister— catch tank— purge solenoid — check valve — UIM. My only goal is to not have fumes engulfing my car or its passengers so I’d rather not reroute it under the car either. My question is, can I just run a line from the hardline to UIM with a generic check valve in place so boost doesn’t go to all the wrong places? Thanks for any help!

 

You might get some unpredictable changes AFR in idle or cruising situations if you do it that way.

 

I live in Texas where cars 25 or older only have to meet safety standards.
Running a single turbo setup with no emissions control.

I removed most of the parts for the gas fume system.
The only parts left are the metal pipe going from the canister to the engine compartment and the canister input hose from the gas tank.
I redid my fuel system piping by using the two large fuel lines as parallel input lines to the injectors from the fuel pump,
and now use the smaller fume line as the fuel return line to the gas tank.

The canister input hose is repositioned up into the bodywork.

I never smell gas fumes from this and the fuel tank retains pressure as the stock system does.

 

but if you added the purge solenoid back it would work?

 

So it’s kinda sounding like leave open or remove are the only two options here lol

 

Not necessarily... Need to get more details on your particular setup, and what components of the evaporative emissions system you still have installed. From your original post, it sounds like you're smelling fumes, and want to eliminate that problem, so the "leave open" path is not even a viable option.

So how is your FD setup? Stock twins, single turbo, etc.? What emissions components were removed or molested? The OP mentioned that the you have the open hard pipe by the firewall, so I'm guessing your setup may be just like mine - see FSM diagram below; I'm missing all of the evap emissions components highlighted in yellow. Running a single turbo, and like yours I have the open hard pipe by the firewall, and all of the evap emissions components shown from there out to the gas tank are installed and in working order. My cabin will pick up some fuel stink if the car is stored for any lengthy period (week or more) with the windows closed, and if I drive it on a warm/hot day with less than 1/2 a tank of gas with the windows open, I'll smell a strong fuel vapor odor. Suspect what happens is with 1/2 tank or less, the fuel heats up more in operation, vapor pressure in the tank overwhelms the ability of the charcoal canister to store them, and they exit from that open vent pipe on the firewall and end up in my nose.

You should take an inventory of the evap emissions components between the tank & the hard pipe on the firewall and report back what you have (stuff not highlighted in yellow below).

 

Your situation sounds exactly like mine lol I have a 20b swap, zero emissions related items under the hood, single turbo, hardline in engine bay, nothing from the hardline to the canister has been touched

 

Yup, same as mine except I'm rocking a 13B. What I'm doing is I added a purge solenoid valve, and one of Dale's Viton check valves, plumbing it exactly like it is in the FSM diagram, but without that small OEM catch tank (just running hose). For control of the solenoid, I'm assigning the solenoid to one of the spare outputs on my Link G4+ ECU that can do full PWM control, similar to how one would control a boost solenoid. A simple on/off type control might be sufficient here, but I wanted to replicate the OEM control strategy as much as possible. Basically the plan is to have the purge happening (i.e., solenoid fully open at high duty cycle) during low-to-moderate load cruise conditions only, between about 1700 ~ 4000 RPMs, and closed everywhere else. You don't want purge happening during idle, overrun fuel cut, under boost or high load vacuum conditions. More detail on what I did mechanically is in my build thread here https://www.rx7club.com/build-thread.../#post12580556 and in this thread, starting on post #40 https://www.rx7club.com/3rd-generati...ssion-1152638/

I postponed the wiring harness tweaks I need to make this purge valve operational till winter hibernation, but will update you when I get it working. Below is a screen shot of the purge solenoid control mapping I'm going to start with.

 

that’s great, I really appreciate the information! Will definitely be utilizing that lol what purge solenoid valve did you purchase?

 

It's an OEM Mazda part used on Protege's, Mazda 6's & RX8's from the early thru late 2000's. Part # for it is in that thread I linked above - not my build thread, the other one. It cost me < $15 or so, and you can PM Dale for the Viton check valves.

 

awesome, thanks so much I appreciate the information!

 

Did you ever sort this out? If you're smelling fumes, check the vacuum chamber on top of the fuel tank that the vents go into, and then it goes to the charcoal canister. Mine was cracked in half pretty much the whole way around. Once I swapped it to a T fitting (like they did on FDs in 95 or 96 and on), no more issues.