EVAP Plumbing 1972

[Ted Z.]

Has anyone eliminated the function of the EVAP CANISTER and plugged the line going to gas tank, at the canister. (Keeping of course the PCV and EVAP hose to carb.) I ask because I'm not sure of a previous owner's work when he put in a new gas tank. Also, I've read of idle stumbles if EVAP system is compromised; mine stumbles a bit. Thanks for feedback. Ted (Newbie to forum)
I apologize for not sounding like an NCRS restorer; lol.

[Patrick H.]

Re: EVAP Plumbing 1972

Did you check to see if the hoses connect to the upper left portion of the gas tank?
Not that easy to see with the muffler there, but you can reach up and feel it. There should be a plastic separator valve there.

There are a LOT of reasons for the engine to stumble, and the Evap system isn't on my top 10 - if at all.

[Ted Z.]

Re: EVAP Plumbing 1972

Thank you for the quick response Patrick. To remove the stumble at idle, while in gear, I have given the car a tune-up, including new wires. (Previous owner put in a Petronix module). I also used some Seafoam a few times over the past year. The stumble is very slight but noticeable by me. I could write a narrative here but I think you understand the dilemma.

Regarding the disconnect of the EVAP system, it was just a long, long shot to eliminate any possible issues caused by 49 year old system; and, included an after market gas tank put in by a DIY.. In short, my thoughts were to set up a 1969 system wherein the gas cap would be vented, and, it didn't come with a charcoal canister. I would leave everything in place, just plug off the canister line at the PVC. Hence, the only active PCV-EEC hose would run from PCV to carb port. Again, I don't want to overwrite here. Hence, my question was actually more related to what harm would be done if I plugged off the EVAP system .

The matter of idle stumble was very small as it relates to this thread.. Thanks again for response. I will eventually start a new thread on idle stumble. I'm sure I'm going to love this forum. God bless, Ted

[Patrick H.]

Re: EVAP Plumbing 1972

I think you first need to find out if the current tank has the ports for the Evap system or not.

If totally disconnected, you WILL notice more gas fumes when the car sits.

[Ted Z.]

Re: EVAP Plumbing 1972

Thanks again for the advice. I will definitely check to see if there is a separator on the tank. As it stands now I do not smell gas fumes with the canister attached. Last question, did the 69 Corvettes give off gas fumes in garages?

[Patrick H.]

Re: EVAP Plumbing 1972

Last question, did the 69 Corvettes give off gas fumes in garages?

Yes.

Even a later car will do it if the system is not perfectly sealed. After 50 years, most aren't.