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Thanks Six. I was over thinking things before, I'm going to keep everything on top of the tank stock. I haven't decided whether or not to keep the charcoal canister but either way I'm going to run a line up near the diff and VTA (with a filter just in case).
So, the answer here could be to simply plumb the rollover valve directly into the TPCV, then vent that (through a filter) via a hose to some safe point under the car.
That is what I did on my last race car and never had issues or got questioned during tech.
Sorry to bring this back from the dead but I'm looking to mess with this soon. I've attached a diagram of the EVAP system for the shop manual. I'm not sure why you would want to connect the TPCV with the Rollover Valve as people were saying earlier because they're already connected up at the filler neck.
Seems to me that the best course of action would be to disconnect the line before it goes into the TPCV (#7) and run a hose to a filter under the car. Then you could remove the TPCV, charcoal canister, catch tank (in the engine bay), etc. You guys see any problems with that?
I deleted all the evap/charcoal stuff on my 99 a few weeks ago and just ran the car on track for the first time this weekend. I started off with the tee'd lines as shown in the original post, along with the spring removed from the stock gas cap. Stock gas cap normally allows flow during vacuum but no flow during positive pressure. Removing the spring allows gas pressure (AND liquid fuel) to escape through the cap.
I got black flagged twice because the corner workers said my car was "dumping fuel out of the trunk." Quickly realized it was dumping out of the gas cap, then running down through the drain hole beside the gas cap. "Quickly realized" because when the gas cap was removed and turned upside down, fuel poured out. This was with roughly 1/4 tank. First I tried un-doing the tee setup and just running a hose down to the frame rail, but I still got black flagged again. Finally I switched to an unmodified NA gas cap (one of the corner workers was nice enough to trade me for the weekend) and had no problems for the rest of the weekend.
What jamesr242 posted above is exactly what I ended up with.
****DEEP THREAD RESURRECTION. This seems to be the best thread with the most information together.****
I have been thinking of tackling this in my NB2 for a while now but still was never certain of the best method. I put together the following pictures summarizing the 2 methods described in this thread so far. The T method and VTA method.
From my understanding are both the NA miata and possible NB1 use the same emissions system? For the NB2, looking at the Mellens link http://www.mellens.net/mazda/Mazda-M...ion_system.pdf the system is completely different.
For the T method, is the common consensus that the gas gap only flow air into the tank not out. Altering the cap spews fuel.
VTA method, since the path of fuel out of tank would be through the rollover valve, into the fuel neck, back out the neck and to a breather. There should never be any other issues with fuel escaping.
Finally- NB2 miatas? any experience with deleting this system (specifically the rear charcoal canister 5) and implementing something similar to the VTA method? Here is the screenshot from the 2005 mellens diagram.
I have been running my NB2 with 7, 8, and 10 removed with the hardline capped in the bay for a year plus so far with no issues. I plan on installing a Radium fuel filter in the rear for my flex fuel setup and would love to remove the rear canister and VTA to simplify the setup (running megasquirt and its not being utilized).
It appears on the NB2 that the dashed lines mean its in the tank which is the fuel shutoff valve and rollover valve. Thoughts on doing the below?
I had totally forgotten about this thread but I'm glad to see it again. So on my old '99 I did what I said above, kept the charcoal canister and ran the vent line up above the diff with a filter. On hot days once the tank was down to less than half I would get some really strong fuel vapors coming into the cabin. I never got around to figuring out if it was my vent or if it was the rubber fill hoses like people have found over at m.net. That car was "lost" on a mountain run back in 2016.
I didn't realize the NB2 tank was different until I dropped it down to start working on the fuel lines for my V6 project. I'm also wondering what the best solution is to vent this newer style of tank. I'd really like to avoid the fuel fumes/stink like my 10AE had!
Finally- NB2 miatas? any experience with deleting this system (specifically the rear charcoal canister 5) and implementing something similar to the VTA method? Here is the screenshot from the 2005 mellens diagram.
I have been running my NB2 with 7, 8, and 10 removed with the hardline capped in the bay for a year plus so far with no issues. I plan on installing a Radium fuel filter in the rear for my flex fuel setup and would love to remove the rear canister and VTA to simplify the setup (running megasquirt and its not being utilized).
It appears on the NB2 that the dashed lines mean its in the tank which is the fuel shutoff valve and rollover valve. Thoughts on doing the below?
That is how I've done mine. No issues with it, just spliced the hose coming down from the tank with the one going to the filter.
Ok, finally got under my NB2.. indeed the method above works perfect. Some pics below.
Simply pull the Charcoal canister and connect the two 18mm lines from the in and out together. Now to find a way to fit my Radium Fuel filter in this spot with the weird NB2 return/feed T fitting
So I'm trying to put an intake going on to the "colder" side of the engine and want to delete the evap canister up front only for now.
What's the best method? It was easy to loop on my NA but here there is only one hard line and a couple of lines going into the intake manifold. Can I just cap that hard line and the ports on the IM and be ok? Since it seems the vent system vents in the back anyway?
I just want to get rid of the crap up front for now and can do a better method later. Thanks!
I came across this thread because I'm doing this currently and found that my nb1 (2000 LS suspension package I think?) Has what this thread has called the nb2 style evap systems. There's no rollover valve above the tank and only one hose coming out if the tank. Just putting that out there to add to the information.
10-09-2015, 01:39 PM
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