ChrisRX8PR

I am building a One off intake manifold for my single turbo RX-8 and I have a questions about the fuel tank breather:

In OEM form the car does not have a return line and has a small solenoid that connects the breather line(same size as the fuel feed line) to a vacuum nipple on the OEM intake manifold.

Now I am using the stock feed line as a return and I routed my own 1/2" feed line turning it into a standard return system.

Is the breather still necessary now that I have a return system? What are my options on it? I could just install a nipple in the intake manifold I am making and connect the solenoid between that and the breather line with some vacuum hose but I am trying to clean up the engine bay and this would add to Octopus of hoses I currently have so if I could do away with it I would.


Thanks in advance.

Chris

p.s.I am asking here because not many people have RX-8's with return systems and the experience here is abundant with this.

Busted7

I would guess the rx8 system replaces the charcoal cannister, so if you removed it completly you would have to vent the fuel tank to prevent over pressureing the tank.

I removed the charcoal system and vented the gas cap and have no problems or leakage.
Im sure there are other ways so guys help a fellow rotor head out!

ChrisRX8PR

Hmmm....I see...you mean venting the gas cap as in not having the gasket installed or drilling a hole etc? How about smell, do you ever get a "wiff" of gas during stops or while turning? Does it ever seep out of the vent?

And no the RX-8 does not have a charcoal system like the FD. Instead it just sucks the fumes through that breather solenoid into the intake manifold and burns them in the engine.

Thanks.

Chris

p.s.anyone else???

classicauto

iTrader: (3)

I'd recommend a charcoal can of some type, or at least a vent to allow the tank to vent pressure/vaccum. Especially sinceyou're running a big fuel pump (i'd imagine anyways given 1/2" feed line ) you'll want to make sure the tank can breathe. But having no charcoal to filter the odor may make it smell gassy.

Of course, plenty of people chuck their charcoal cans and say the car doesn't stink.........but everyone's sense of smell is different I guess........because I know mine REEKS if I just pull the hose off.

I'd absolutely say it needs SOME type of vent though, whether its a simulated OE system like it had, or an improvised vent or improvised can.

ChrisRX8PR

A charcoal can? Where can I get this?

My car just had the ECU open that solenoid once in a while and the vacuum from the intake manifold would suck up the fumes and they would go through the engine. That is how it was OEM.

Any other suggestions from people that have either altered this or eliminated it?

Thanks,

Chris

NewbernD

iTrader: (1)

I don't know about the RX-8 specifically but in general, newer emissions controlled cars have several vents. One, the line that goes to the purge solenoid on the intake manifold, and one that goes through a charcoal canister to a vent that is usually by the gas filler. The one by the filler has a solenoid that can seal/vent. There also a pressure sensor on the fuel tank.

Every now and then, the computer will go into an evap test mode. It will seal the vent by the gas filler, open the purge valve while the car is under vacuum, and then close it to create a vacuum in the gas tank. It then uses the pressure sensor to figure out if there are any leaks in the system.

I'm fairly certain that your RX-8 has a charcoal canister and another vent somewhere. Try capping the purge line and blowing into the fuel filler. It doesn't take much pressure and you will hear air being vented from somewhere.

classicauto

iTrader: (3)

Junkyards!

FC's have them, as well as numerous other "older" cars

And the above post has some great info on the evap system.

Rocking Rotary

iTrader: (14)

They have a few valves to install in the tank or sending unit to help it breath and cut down on the fuel vapor smell. Make sure it does have a roll over check ball just to be safe.

Busted7

My tank would smell at first but i enlarged the hole in the cap and it stopped. There is also a screen on the fd fuel cap to prevent fuel spitting. But the charcoal can should work, i have the one out of my fd!

ls2

iTrader: (2)

you need the tank to vent