I've searched several threads, and 9/10 people say to just remove the junk and let the gas tank vent to atmosphere via hardline on the firewall.

I'm tired of the smell in my garage and its carrying into my house. So i'm considering putting the stock system back on the car... but I'm curious if it can see positive pressure (boost).

Please respond if you can shed some light on my question. I haven't been able to get a straight answer yet.

The interesting part about the charcoal system (on my stock integra), is that there is still tons of pressure built up whenever I take the gas cap off. I thought that was the entire point of this system?

 

I would definitely keep the system together. Even in 500 wheel horsepower setups EVAP canister is the best way to be able to have it so that you do not have gas vapors all over the car.

I think what people are referring to is the removal of the stock catch can PCV system. Not the EVAP canister

 

Thanks for the response, I went and picked up a canister today with intentions of doing this.

I dont see the wire/connector though. Previous owner must have cut or tucked the plug, is the solenoid critical to operation of the system? I can hook everything else up and directly run a wire(s) down to the ECU manually if need be.

I still have a few other phantom odors under the hood around the injectors and braided lines, i'll have to track those down as well.

I cant stand the fuel smell

 

I am not completely sure about the solenoid requirement. I admit, have never run a car without any EVAP canister due to exactly the same issues that you're experiencing now. (I eliminated mine on my older DSM and found that doing so was a huge mistake :-( )I personally would go ahead and see if you can try and find a solenoid in order to alleviate the problem completely.

 

Here is the can I grabbed today from an OBD2 system.... I noticed on my stock integra (OBD1) the system is even simpler.

the hose that you see will connect to the hardline on the firewall. the port right next to that is what I will connect to the throttle body.

The port off the back of the solenoid is what I need to sort out. I dont have the civic manual so i'll try to find that online. Maybe I can just tee that with the line that will go to the throttle body

 

the plug that goes on that small nipple, mine broke off. what can i use to cover it? i believe the cover that was on it was a breather of some sort.

this evap can is the one that sits behind the intake manifold. i have 95 gsr ob1, not trying to thread jack but trying to get help on the same thing

 

Just checked the manual, there are more parts than I originally considered. The solenoid above from my picture actually connects to a 3 way valve under the hood.

There is also a 2 way valve in the rear of the car (and another solenoid) before the fumes make their way back up under the hood.

I was hoping for an easy button doesnt seem this is going to be simple as the previous owner also removed the 2 way valve back by the tank and the corresponding solenoid.

 

All a evap canister is a filter, there are solenoids controlled by the ecu to limit the amount of air into the engine. I kinda get the impression from the little digging I did that its normally closed on honda and most other late model cars. I really wonder if they even need vacuum when all your worried about is the fumes in the garage. The fuel cap has a one way valve that only lets air in. Gasoline has a fairly high vapor pressure it will continue to evaporate.

Point being I bet if you hooked up the vent from the gas tank to a evap canister and left the other end open it would solve your problem.

 

thats assuming the canister would kill the fuel odor, which is hard to believe.

I think the canister still needs connected to the engine via throttle body port so that there are no fumes to atmosphere.

 

on my em1, i capped off the port from the throttle body where the hose to the canister goes. and the plug is unplugged. no fumees at all

 

I just eliminated the whole system on my drag car EM1 all the way to the tank. Will this be alright with the evap check valve capped off on top of the tank and the only vent is through the filler neck?

 

If there is no vent, pressure will build in the tank. It needs some sort of a vent.

Edit: the stock cap lets air in but if the car sits in the hot sun there will be no where for the vapors to go and pressure will build in the tank.

 

Almost every Honda i've owned lets off serious amounts of pressure each time I undo the gas cap to fill up the tank.

I cant seem to understand how that is the case when all of those cars have had the OEM EVAP system in place.

It also seems to contradict many of the suggestions I've been seeing on these threads, I understand capping the tank is a bad idea... but why do all of the cars blow off pressure when the cap is unscrewed?

 

I know when I capped mine off the pressure build up was 10x worse than stock and drilled a little hole in the cap so it wouldn't anymore. I was fearful that at some point the pressure buildup would effect engine fueling.

 

The EVAP/purge solenoid will open when the ECU thinks it should, not really sure when it does. On an obd1 system it appears to use the purge solenoid to apply vacuum to a diaphragm valve on the canister. That diaphragm allows a port to open that vents fumes to the throttle body directly before the throttle plate, creating suction from the venturi effect. I've also seen it mentioned that it could be a diaphragm pump, creating suction from the pulsations inside the plenum.

OBD2 systems appear to vent it directly into the plenum, and use a second solenoid valve (on the canister) to vent clean air into the cansiter.

The best way is to route the charcoal canister's main exit line to a spot between your throttle body and air filter. You may still get some fumes coming out via the filter if it sits a long time, but they'll mostly be drawn in while the engine is running. Just make sure you use a canister that has an open vent tube.