If I pull the evap canister out what should I do with the hose from the fuel tank (plug it, leave it open)? I can put on a vented gas cap. Larry
Don't do it!
On hot days after the fuel in the tank is adequately warmed up after driving for a while, fuel vapors will build up in the tube to the point of raw fuel dropping on the ground when you park and the elevated location of the line in the stock location beneath the deck lid will not stop it. I discovered this after failing to reinstall the canister after an engine swap.
Don't even think about capping it either because my first brush with the line in question is when it got clogged and caused the fuel tank to swell and make crumpling noises under the same conditions, not to mention the whoosh of fumes from the pressure build up in the tank when you remove the cap.
I am doing an engine swap to a carbed engine, so lots of stuff can come out of the engine compartment. If this can come out too it would be nice. Don't need it for emissions, What did old cars do before they had them? Larry
Charcoal canister is not really engine related so you should still use it even with a carbed engine. If you find it ugly move it some where less visible. Dan
I can leave it, what do I do with the two vacuum lines that hook into the top? Larry
Theoretically it should contribute to better fuel economy by redirecting fuel vapor to the engine for consumption as opposed to venting to the open air. A vent tube is a necessity on any gasoline tank, but as mentioned regarding the fuel vapor's ability to pool into liquid form as it is vented from the tank, it is best to have that vapor escape into the engine where it can be burned and the evap canister helps in this process. Look at the vacuum tube diagram for an appropriate method of connecting it to the carb intake system.
I have looked at all the diagrams, they show the small two hoses going to the TBI. I am thinking that one is the vent line and the other some how controls the venting? Any one know which is which? Wlould pulling vacuum on one open the vent on the canister for the other line? Larry
One line goes to ported vacuum, and the other goes to manifold vacuum. The ported vacuum line opens the valve in the canister, allowing manifold vacuum to pull the fumes into the intake. If I remember correctly, the very top one (which should be the smaller of the two) is the ported vacuum line. You can verify this by tracing the line back to the ported vacuum nipple on the bottom of the throttle body.
Port will pull a vacuum when throttle is open. Just use a vac gauge. Likely 2 on top but you need a gauge to test because internal plumbing...
In some text... top/control to port vac bottom/vent to manifold vac
For reasons only GM knows... they run "backward" on many cars, including Fiero. Maybe vent port flows too much air when connected to manifold vac. Proof? In some/all Fiero, Top port on Evap also used by Cruise Control. CC needs Manifold vac to work.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
No charcoal filter here. I just plumbed the gas tank vent tube to the air filter box. Haven't experienced any ill effects in three years
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
I would keep the evap. If you vent it, it will allow fumes out in the day as it warms, and it will draw in air at night as it cools. Ethanol attracts moisture and so having it vented will increase corrosion in your fuel system by the additional water that will get in there. Plus there is not HP to be gained by deleting it.
------------------ 84 NB, 3800SC, E-85, VS Cam, 3.0 Pulley, 4T65E-HD, HP Tuners, AEM Wideband, Regal GS Gauges, S-10 Brake Booster. 1/4 mile -12.05 at 111.7mph
For reasons only GM knows... they run "backward" on many cars, including Fiero. Maybe vent port flows too much air when connected to manifold vac. Proof? In some/all Fiero, Top port on Evap also used by Cruise Control. CC needs Manifold vac to work.
Guess I am really confused now. So which hose goes to which vacuum? Larry
The two hoses that normally go to the lines on the trunk wall. You can use a vacuum T to bring them together. The other line goes to the tank in 84-86 or the over flow tank in the 87-88.
quote
Originally posted by Joseph Upson: On hot days after the fuel in the tank is adequately warmed up after driving for a while, fuel vapors will build up in the tube to the point of raw fuel dropping on the ground when you park and the elevated location of the line in the stock location beneath the deck lid will not stop it. I discovered this after failing to reinstall the canister after an engine swap.
Hmmm. That explains a strange problem I had on my 3800na swap. Before I hooked up the EVAP canister I had raw fuel leaking on the floor near the back of the fuel tank. Soon as I hooked up the EVAP canister it went away, I assumed it was the EVAP can but wasn't sure...
Isn't it strange that after a bombing, everyone blames the bomber, his upbringing, his environment, his culture, his mental state but … after a shooting, the problem is the gun?
[This message has been edited by MulletproofMonk (edited 08-12-2013).]
My evap line is routed into the air cleaner cylinder. My car never smells like raw gas. Did not notice a change in gas mileage either. I also hated all the vacuum lines everywhere. It is routed to the outside of the filter, so the filter contains the vapor between the throttle body and filter, or maybe it just absorbs it. I have not noticed any negative affects, and it cleans up the engine bay a lot.
Originally posted by theogre: In some text... top/control to port vac bottom/vent to manifold vac
For reasons only GM knows... they run "backward" on many cars, including Fiero. Maybe vent port flows too much air when connected to manifold vac. Proof? In some/all Fiero, Top port on Evap also used by Cruise Control. CC needs Manifold vac to work.
I was just blowing/sucking on the two lines to figure out if the charcoal canister system can work with my turbo setup. It appears that the stock charcoal canister system can work with a turbo, without any modifications. When I blow into either line alone, or both lines simultaneously, airflow is completely blocked.
In the Fiero 2.8, I have another theory why the vent port is connected to ported vacuum. If fuel vapours are introduced at the throttle body, I suspect that they will be sort of equally distributed among the cylinders. If the vent port were connected to a nipple in the plenum, fuel vapours would be drawn mostly to the nearest cylinder. Usually one wants all cylinders to run with the same AFR.
Just some ideas that came to mind after studying the charcoal canister system...
Originally posted by pmbrunelle: I was just blowing/sucking on the two lines to figure out if the charcoal canister system can work with my turbo setup. It appears that the stock charcoal canister system can work with a turbo, without any modifications. When I blow into either line alone, or both lines simultaneously, airflow is completely blocked.
In the Fiero 2.8, I have another theory why the vent port is connected to ported vacuum. If fuel vapours are introduced at the throttle body, I suspect that they will be sort of equally distributed among the cylinders. If the vent port were connected to a nipple in the plenum, fuel vapours would be drawn mostly to the nearest cylinder. Usually one wants all cylinders to run with the same AFR.
Just some ideas that came to mind after studying the charcoal canister system...
Think "Dumb" EVAP is not made to have pressure on either line regardless doesn't let air flowing backward. You need to find older turbo setup and get FSM and VECI label for that car. Many the EVAP can too.
Fiero and most others Both lines should go to Carb/TBI/TB. "backward" GM setup flips lines but still doesn't purge at low RPM or at idle because Purge line still goes to Port Vac on carb/TBI/TB.
My guess is "right way" had some type of problem that flipping solve. Maybe purge line allowed to much air and engine sees vac leak, EVAP can has problem or both.
Beside trapping fuel vapors... Most or All EVAP systems can get "poison" getting crap in air to purge the gas fumes. VOC and more can get into the charcoal and ruins it. Liquid fuel can to this to and big reason why 87-88 have extra expansion in right rear quart panel.
Some reason the fumes cling on outside of carbon and easy purge air flowing over them. Liquid gas and many other things kills this trick. So Flipping lines might allow less air to purge w/o redesigning the can to solve these issues.
No charcoal filter here. I just plumbed the gas tank vent tube to the air filter box. Haven't experienced any ill effects in three years
Seven years later all is still OK. The only disadvantage might be with a back fire but those don't happen with an engine in good condition
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
I was just blowing/sucking on the two lines to figure out if the charcoal canister system can work with my turbo setup. It appears that the stock charcoal canister system can work with a turbo, without any modifications. When I blow into either line alone, or both lines simultaneously, airflow is completely blocked.
In the Fiero 2.8, I have another theory why the vent port is connected to ported vacuum. If fuel vapours are introduced at the throttle body, I suspect that they will be sort of equally distributed among the cylinders. If the vent port were connected to a nipple in the plenum, fuel vapours would be drawn mostly to the nearest cylinder. Usually one wants all cylinders to run with the same AFR.
Just some ideas that came to mind after studying the charcoal canister system...
There are 3 hoses on the canister, the biggest one comes from the tank the one from the canister top is the vacuum that comes from the intake and the one below the top one is a ported vacuum hose that goes to the throttle body.
The hose that comes from the intake (vacuum) is used to open the valve on the canister to vent the canister by the ported hose No vacuum and the valve still close or with a pressure of a turbo the valve remains closed (as pmbrunelle mentions it) and the ported hose works only off idle does not purge at idle.
We can not reverse these 2 hoses, the top hose is a vacuum hose to open the valve, it is not the ported hose.
Seven years later all is still OK. The only disadvantage might be with a back fire but those don't happen with an engine in good condition
Very old thread but I must add that I took my canister off as well last year. Drove 4k miles this summer, New Mexico to Pennsylvania to Michigan back to New Mexico. Never had a problem with a gas smell or leak.
The charcoal canister is kind of mandatory for my Fiero.
Since my Fiero is a frequent tenant in my dad's garage (the rent is very cheap ), and my dad has a very sensitive nose, my Fiero better not emit any fuel vapours...
If the gas cap on a car is left undone, or there's a jerry can that was recently used in the garage, my dad will smell it. I want to take the necessary precautions to ensure that my Fiero remains a good tenant.
The charcoal canister is kind of mandatory for my Fiero.
Since my Fiero is a frequent tenant in my dad's garage (the rent is very cheap ), and my dad has a very sensitive nose, my Fiero better not emit any fuel vapours...
If the gas cap on a car is left undone, or there's a jerry can that was recently used in the garage, my dad will smell it. I want to take the necessary precautions to ensure that my Fiero remains a good tenant.
LOL, that I can understand. My wife is very sensitive to gas and grease odors. Do not want to upset the landlord.
