3800sc evap canister (Page 1/2)
johnguzman1212 MAR 18, 09:03 PM
ok...what do I do with the two lines that went to the TBI on the duke...I have a 3800sc from a buick Riviera. I did the search function but he has the evap system I don't... you know the two hard lines on the trunk wall? can I just put a u tube from one to the other lol?
Riddick85 MAR 19, 10:43 AM
I just finished my 3800 and would like to know this info too since it is starting to warm up outside. From what I gathered one needs to go to vacuum. Don't know other than that.

I read you can delete the canister and put on a vented gas cap too
Darth Fiero MAR 19, 06:54 PM
If you do pretty much any engine swap and wish to retain the Fiero's EVAP system and keep it functioning, you'll probably need to install the EVAP purge solenoid that came with the donor engine that you're swapping into your Fiero. On the stock Fiero engine, the throttle body had a ported vacuum signal that controlled the Fiero's charcoal canister's purge function, mechanically. Newer engines usually lack these ported vacuum sources, so you will need to wire in an EVAP purge solenoid to control this function. The purge function is needed so the charcoal canister can be purged of stored gasoline vapors so it does not become saturated (which will quickly occur if it is not regularly purged). As the fuel heats (by daytime warming or by the engine running and the fuel circulating thru the fuel rails), the fuel vaporizes in the tank and this excess vapor must be dealt with - otherwise it would just leak out to the atmosphere causing a raw gas smell or could even create a dangerous situation if the car is stored in a sealed garage. Below is a vacuum diagram of how to hook up a computer-controlled EVAP purge solenoid to the existing Fiero charcoal canister.



-ryan

------------------
OVERKILL IS UNDERRATED

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

johnguzman1212 MAR 19, 11:11 PM
ohhh I see so just tee together and put on evap solenoid and run line to the little thingy that has one big nipple and two little nipples ? so no electrical connections? I still got the egr stuff I removed from the 3800SC just cant remember what it looks like
johnguzman1212 MAR 19, 11:17 PM
wooo I had my evap deleted from the programming I think...what do I do now?
Darth Fiero MAR 23, 07:56 PM
Yes, there will still be an electrical connection - to the EVAP purge solenoid you'll need to install.

Even though I disabled the EVAP related codes in your custom PCM tune I made for you, the EVAP purge solenoid will still function if you wire it up to the PCM.

-ryan
Adjustso3 MAR 25, 02:43 AM
So what do most guys do ? Do they bother hooking up a canister ? I've looked at many pics but don't see any canisters.
Darth Fiero MAR 26, 01:21 PM

quote
Originally posted by Adjustso3:

So what do most guys do ? Do they bother hooking up a canister ? I've looked at many pics but don't see any canisters.



I don't know what most guys do. I can tell you that every swap I do in-house leaves here with a charcoal canister and functioning EVAP purge solenoid if it is required.

The job of the charcoal canister is to store raw gasoline vapors generated by fuel heating (which is normal operation while the car is running and fuel is circulated thru a hot fuel rail on the engine). Heating the fuel causes it to vaporize and expand in the tank, so you have to vent the tank so excessive pressure cannot build. Without a charcoal canister, these vapors would have to be vented to atmosphere, which can create an annoying raw gas smell or a potentially dangerous condition if the car is parked in an enclosed garage.

The charcoal canister can only store a certain small volume of gas vapors and it must be purged periodically. Stock Fiero engines used a ported vacuum source on the throttle body to open a valve on the canister to purge it at part throttle operation. Modern engines no longer have ported throttle body vacuum sources so a computer-controlled EVAP purge solenoid will need to be used to take over this function.

You should not run a canister without having some means of purging it and you should not plumb constant vacuum to the canister to continuously purge it (as this can cause engine running problems). So, the rule of thumb is if you are going to do a 3800 swap into a Fiero, add the EVAP purge solenoid to the stock Fiero charcoal canister as I showed above and everything will work properly.
Adjustso3 MAR 26, 09:19 PM
Thanks Darth Fiero. Is the purge solenoid only vacuum controlled or is it electrically assisted ? If electronic where do you connect the wires ? Should a new canister be purchased or is there a canister that you recommend along where to place in the engine bay with the 3800SC ? Thanks for your time.
cmechmann MAR 26, 10:10 PM
Any 3800 SC from 92 on has a purge control function in the PCM. The wiring for the control should be in harness. The power feed can come off the same circuit as the charger bypass solenoid. The purge control solenoid should have been mounted between the intake and one of the valve covers on the donor engine on series II. If not someone through it away. On Series 1, could have been mounted on the canister. It is simpler to use the controlled set up rather than all vacuum. The PCM is expecting it. You will need to have the vent function and tank pressure monitor functions edited out of your PCM programming, but leave the purge function on. I had mind set up just like the diagram shown earlier with the stock Fiero canister and had no problems with it. If you are careful, you can pop the top off the cap of the vacuum control on the Fiero canister. You then can remove the plunger from the rubber diaphram under the cap. Replace the cap with the diaphram to seal the cap and plug off the top vacuum port. This will allow the canister to vent with only having to have 1 larger vacuum hose. You can use a vacuum single port canister, but most are too big for the Fiero bracket. The solenoid will be controlling the vacuum so you won't need the plunger under the diaphram to be opened by vacuum. Make sure the vacuum source is full vacuum, not boosted pressure. On top right next to the throttle body where you would also connect brake vacuum.
If unsure, go to a pick and pull and find a Series II SC and look at the vacuum lines. Snag the solenoid and hoses if you are missing yours.

[This message has been edited by cmechmann (edited 03-26-2015).]