I was wondering about removing the charcol can when I install my dfi this month. I've ripped out my entire tpi harness and I want to know if I should keep the can, get rid of it or what. Emissions is not an issue, but I don't know if you get a lot of gas tank fumes with out it. Thanks

 

Just plug the vapor line and you should be fine.

 

if you plug it.. does the tank still vent? I removed mine in my lt1 swap.. wondering if i can remove the line at least to behind the motor.. and if possible block it off.

 

Our tanks have 4 lines. Fuel feed, Fuel return, Vapor Purge, and the 4th line (atleast on thirdgens) goes to a little valve next to the tank.

I don't know for sure if that is an in valve or an out valve. My guess is that it is in an inlet valve. If it's an inlet valve then when you use fuel it brings in air to replace the space the fuel held.

If you block off the vapor line, it might not breathe right. If it needs to breathe at all. On my jimmy I've just got the line open.

 

i beleive that if you plug the vapor line, then you can build pressure in tank, the breather filter should have a check valve, so it only allows air into the tank. same with the vent line, it his a valve (located right by the caninster, that keeps it from sucking air into the tank.

 

The main valve for the vapor line is in the tank. Its like a pcv valve.

 

i guess by that then, I can plug the line going to the charcol can??

 

You really should put a breather in. Normally the excess fuel vapor would be taken up by the can. The pressure relief valve on the tank allows it to build quite a bit of pressure.

 

Note that if you have to pass emissions, sometimes the vapor from the tank can throw the emissions off.

 

The *valve* in the 4th line is a pressure blow off type.
Without the charcoal canister, the tank won't vent.

The ecm expects a slight vac leak when the Charcoal canister is supposed to be on, actually it can account for slightly rich or lean.

If you plug the side going to the engine, you really should have the chip redone to have things done correctly.

One way or another the tank needs a vent, and the vent needs to be able to flow as much air as the engine can use fuel. And it might be more they you'd expect with a healthy engine.

And if your really into *it*, you'll reroute the return line so it doesn't pick up so much heat off the tranny.

 

Grumpy's right, you don't want to just block off the lines, the tank will not vent and will build an enormous amount of pressure. I know from first hand experience. I put mine, charcol cannister, back on and ran the line that was originally going to the old carb. and put a small filter on the end of the hose and dropped it down by the power steering box and tied it off neatly. Very few fumes noticable, and the gas tank doesn't do the pressure thing. Vader gave me that idea and it does work.

 

so you hooked up the can, but still vented it to the air through a filter? I would just put it into the TB.. anyway.. I really don't want to put it back on.. I have no emmisions per say to pass. and I have programmed it out of the PCM with tunercat.. just wondering if I can block it.. I'd say the answer is no.. I may cut the line short yet.. or leave it.. I noticed that b4 i took the can off, the tank would build enough pressure that you could hear the pressure relieve when you opened gas cap.. now nothing.. if it won't hurt anything.. i may just leave it be..

 

Best solution I found was a gas cap off of an early vehicle, such as a 3/4 ton pickup out of the early 70's. My dad happened to have one lying around that worked, so I know they exist. Odd thing though, the chain auto places I searched, listed the same gas cap with EVAP or without, which is not correct. The cap MUST be vented on non-EVAP vehicles, unless there was a breather off of the sender, and say, post-1968 vehicles, I've never heard nor seen a breather tube off of the sender.

Personally, I could never think of a "good" place to run just a vent line (don't like the idea of it underhood, or anywhere near heat) and I didn't like the idea of leaving it "open" so that the tank could theoretically pick up more condensation than necessary.

Now that I think about it, condensation can't be any more of an issue than with the stock setup...you are still taking ambient air, humid or not, and allowing it into the tank. But at least it vents in a "safe" area.

I've heard that this will eat paint eventually, but I'm willing to run that risk compared to the other options.

 

i heard of the cap option.. my beef was that the can takes up space.. more importantly the vapor line runs close to the header.. too close.. wold like to remove line altogether.. perhaps i may investigate putting the can somewhere else.

 

To clarify what I'm looking for. I don't have to worry about emissions but I do worry about saftey. I've ripped out my tpi harness and I'm installing gen 7 with out any of the original emissions crap. I've got an emissions exemption so I don't need it. I think that I would like to keep the can since that seems like the best thing to do. Since I won't have the original computer to send a signal to the valve(?) on the can how do I hook it up? What is that valve(?) do? Thanks.

 

well, a buckshaw way would be to use a relay and a switch, use relay to trigger evap solnoid.. you could even get an electronics shop to gear you up a circuit to trigger the relay say every 5min. they do that with about $5 worth of parts.. and then you wouldn't need a switch..
best of my knowledge is that the computer completes a circuit for the evap can.. probably making a GND.. and that energizes the solinoid to open and allow the engine vacuum to suck the can dry into the intake. then the computer opens the circuit (breaks the gnd) and that closes the solinoid to allow the can to build up fumes again...

 

I know the 2bbl S10s and thirdgens had a charcoal can ran without a computer. I'll go look at my jimmy and see how it's done. You might consider picking one of those up since it works on its own somehow.

 

Remove the Line at the tank...there is a rubber section at the tank.... Put a cheapo imort fuel filter on to vent the tank.... the fumes are Barely noticable UNLESS you stick your nose right next to the filter....

I also tried to PLUG the line and use a vented gas cap BUT that gave me a fuel odor while sitting at stop lights and was also a PITFA to use...

Bottom line is on a TURDGEN ESPECIALLY you need a vent... With the genious design of running the exhaust in the rear right under the gas tank as you drive the fuel heats up and builds Positive pressure....the factory vent is a 1 way valve letting air in preventing a vacuum situation only...Sooo you must have a way to vent the air out....