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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Hey Guys, I think I have an answer for you guys who have bad EVAP systems. At least later model 3rd Gens. UPDATE: Scroll down to post#8, this looks to be working very well. You can check your specific year and see if this is applicable. I've done research and it appears you could take the evap canister from a 1993 and use the 1993 solenoid. The difference is the 1993 canister is just a canister, and the solenoid is mounted remotely. The canister purge hose runs to the solenoid and then from the solenoid into the throttle body. Electrically, I'm not certain if the ECM puts out a simple 12V signal (via ground) or if it is using PWM signal. Both generation manuals simply state that the ECM closes the loop to activate 12V.
I've got parts ordered and will let you know. I'm not certain if my purge solenoid is working, will find out soon. My evap canister is tucked under the bumper because of SLP fresh air intake, so not super easy to get to. Only want to take it apart once.
Ha ha, probably not on a stock 305 TPI. I'm not sure, because I installed it while getting the car running again for the first time in 25 years. but I doubt it. but it sure looks cool, and on hot Texas summer days (100+), its got to help, at least with gas mileage
Keep us posted with the new EVAP set up, this is some good work on your end. The lack of replacement parts for this system would make this a good solution if it works out.
I'd imagine just about any canister that has same setup as the 4th gen would work, it just happens to be that the 4th gen canister looks to be about the same size as the 3rd. I don't have measurements yet, but will post some photos of them side by side and get a diameter measurement on both. All the canister does is sit there and look pretty, and hold fumes until the solenoid is activated. that is, it holds fumes as long as the fuel vent valve that leads to it is doing its job.
Thank you for posting this info as this look very promising. My evap canister and purge solenoid are shot and i have been looking for a replacement. I was thinking of using the one from a 91 Corvette, but this looks better.
Well Guys, I think this is going to work. Charcoal canisters almost exact same size. Connectors are identical. A pic of the final install before buttoning things up. Gonna run with it for a while and see how it does. Started the car and let it run to temp, but that wont activate the solenoid, need to let it go down the street - didn't have time. Pardon my zip-tied solenoid. Haven't hunted down the proper mount.
As long as you have the similar setup. Make sure you're solenoid operates off 12V (probably does), try to check your wiring for your specific year. I haven't tested this fully yet, need to road test it. But I'm pretty confident its gonna work. Also, there are other vendors that have these parts, you don't have to get these specific ones, just use the same GM part number, which I think is good from 1993-1995.
I don't know how to tell if canister is worn out w/o opening it. Have read accounts of guys opening them up to find the charcoal has gone to dust. I did test the solenoid, using 12V from the battery - you can hear it open. It's still good!
As long as you have the similar setup. Make sure you're solenoid operates off 12V (probably does), try to check your wiring for your specific year. I haven't tested this fully yet, need to road test it. But I'm pretty confident its gonna work. Also, there are other vendors that have these parts, you don't have to get these specific ones, just use the same GM part number, which I think is good from 1993-1995.
I don't know how to tell if canister is worn out w/o opening it. Have read accounts of guys opening them up to find the charcoal has gone to dust. I did test the solenoid, using 12V from the battery - you can hear it open. It's still good!
Thanks for the info, last time I had mine out for the SLP cold air box install I gave it shake and it sounded like it was full of sand so it’s likely done. This might make a nice spring project.
I have installed the canister and valve with out any issues. The brackets from the old canister fit the new one perfectly and I was able to bolt it back down in the original location. The purge valve is just tied up for the moment, but I have ordered a 4th gen evap bracket and will find a way to fit that in there to hold it long term.
I found a place on facebook called 4th gen salvage and asked if they had one for a LT1. They do and they will ship it out tomorrow. Once I get it, I can see how well it will work.
I found a place on facebook called 4th gen salvage and asked if they had one for a LT1. They do and they will ship it out tomorrow. Once I get it, I can see how well it will work.
Hey Steve - I noticed you don't' have your air opened on the canister. You may want to look into that for a 1991. My 1990 has it open, it has a hose coming out of it, which connects to a T fitting. from there, 2 more hoses connected. One goes down thru the hole on the bumper splash panel, (this is longer) the other just goes to air (this is shorter)
Interesting. The Air port is not completely closed. It has a small cover clipped on, but is open on the bottom of it. My original looked like that to, I have never seen a hose attached to it. Maybe the difference between a Camaro and Firebird. Do you have pics of that?
I've seen the canister air port both ways. With the hoses and the T, and with the small clip on cover. The cover of course having a slot in the bottom to allow the canister to vent or intake air.
I have no idea why GM changed this up between various cars...
Just ordered the Canister/Purge Solenoid. Thanks for all the research and links you provided LiquidBlue!
This is a great thread. I'll update once I get mine situated.
Hey Guys, I think I have an answer for you guys who have bad EVAP systems. At least later model 3rd Gens. UPDATE: Scroll down to post#8, this looks to be working very well. You can check your specific year and see if this is applicable. I've done research and it appears you could take the evap canister from a 1993 and use the 1993 solenoid. The difference is the 1993 canister is just a canister, and the solenoid is mounted remotely. The canister purge hose runs to the solenoid and then from the solenoid into the throttle body. Electrically, I'm not certain if the ECM puts out a simple 12V signal (via ground) or if it is using PWM signal. Both generation manuals simply state that the ECM closes the loop to activate 12V.
I've got parts ordered and will let you know. I'm not certain if my purge solenoid is working, will find out soon. My evap canister is tucked under the bumper because of SLP fresh air intake, so not super easy to get to. Only want to take it apart once.
hey thank you for posting this I have a question, should I go withe this new canister setup instead of replacing with a used one,also on this setup would you need to T some of the lines and did this work goof for you
2 problems with used canisters. sometimes the insides are worn out. there is something in there that absorbs fuel vapors. so you can never really know the condition of it. second problem is does the solenoid work? replacing with new guarantees everything will work. That said, I do like to stay factory for nostalgia sake. So it depends on what is more important to you. I wanted this as a backup solution should my factory give out in the future and was probably bored at the time, needing a project. I reconnected everything just as it was connected coming out of the factory. all the same ports are there.
2 problems with used canisters. sometimes the insides are worn out. there is something in there that absorbs fuel vapors. so you can never really know the condition of it. second problem is does the solenoid work? replacing with new guarantees everything will work. That said, I do like to stay factory for nostalgia sake. So it depends on what is more important to you. I wanted this as a backup solution should my factory give out in the future and was probably bored at the time, needing a project. I reconnected everything just as it was connected coming out of the factory. all the same ports are there.
Well not sure if solenoid does work but my car is still original but wanted to replace canister and other evap components I saw. A post on a guy who rebuild his canister but thought wasn’t bad idea to buy a new one. Did you have to T any lines
Well not sure if solenoid does work but my car is still original but wanted to replace canister and other evap components I saw. A post on a guy who rebuild his canister but thought wasn’t bad idea to buy a new one. Did you have to T any lines
No T's were required. was plug and play, other than having to mount the solenoid separately. Mine came with a T from the factory. see post 16
Last edited by LiquidBlue; Aug 21, 2025 at 01:27 PM.
I’m assuming this will work on a 86 as well connectors look the same, I’m gonna give it a shot, my solenoid went out and can’t find a new replacement for the life of me
I think 86 is a bit different setup, but don't see any reason why you could not switch to the newer version. I'd look at the differences a little closer to confirm.
