Charcoal canister question

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jseabolt
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Charcoal canister question

Post by jseabolt » Sat Apr 27, 2019 3:29 am

This does belong in the BS section. I'm curious about something. Something I don't think I have ever heard mentioned on this board. Maybe Fiat guys are just a bunch of auto mavericks.

Have any of you guys ever "restored" the charcoal canister on your Fiats? Have you ever thought about it?

Years ago I was underneath my Spider and near a red check valve, filter or something, there was a clear poly hose that someone had clipped. I had heard these valves or whatever they are can fail and cause negative pressure to build up inside the fuel tank which results in stalling. The quick fix is to cut the hose so the tank vents to the atmosphere. I ended up removing the canister since it was serving no purpose and just taking up space.

One day I cut the canister from my Yugo open just to have a look at what was inside it. It was a sticky/greasy/black mess.

I've been on an MGB forum and there has actually been some discussion on "restoring" the fuel evaporative canister on MGBs. This guy actually has some good MGB videos but here is one where he is showing how to restore the activated charcoal with a propane torch.

https://www.youtube.com/watch?v=6qmLp-cJeCk

On my '77 MGB someone has de-smogged the car. Which is fine with me. That's probably a 30 BHP gain.

All that was left was some sort of vapor separator in the trunk. Which wasn't even hooked up correctly!

I removed it and asked if anyone wanted it and I would send it to them if they compensated me for shipping and some guy said yes he wanted it!

I was told by a few people that I should source this charcoal canister and connect it and get the system working again. My question was why? Some people said, "well it's good for the environment". I questioned one guy if his car still had a catalytic converter. He wouldn't answer me.

Needless to say I drilled a vent hole in the gas cap plunger and plugged off the nipple on the filler neck. The trunk of this car wreaked of stale gasoline where it had been venting into the trunk for so many years.
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rridge
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Re: Charcoal canister question

Post by rridge » Sat Apr 27, 2019 11:32 am

James wrote:
I was told by a few people that I should source this charcoal canister and connect it and get the system working again. My question was why?
For most of us the reason keeping the carbon canister working is that it controls the smell of fuel in the car and in the garage. When I first got my Spider, the original canisters were available for not much money. Fiat had a ten year warranty exposure on emissions related hardware on U.S. cars when they left the U.S. in 1982. Aooarently the canisters were part of the parts stash they left behind and there had not been much demand for them. For some years there was also a GM look alike for the late Spider canisters. Going forward, yes it does make sense to document how to clean them out and refill them with carbon as MG and other owners have been doing.
Richard
'81 Turbo Spider
Rockville, MD
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18Fiatsandcounting
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Re: Charcoal canister question

Post by 18Fiatsandcounting » Sat Apr 27, 2019 11:51 am

Although the charcoal canister is considered part of the emission control system, the only function that I'm aware of it to trap gasoline vapors at various points in the fuel system rather than letting these vapors leak out to the atmosphere. Vacuum from the carburetor or intake manifold then pulls the vapors back into the engine where they are burned. In terms of performance, I can't see how it would have any impact other than carrying along a few extra pounds of weight for the canister and tubing. Small price to pay for not having your garage smell like gasoline whenever the Fiat is parked there, methinks.

As to "recharging" the activated charcoal (carbon), I never thought about it, but from my earlier days in ye olde college chemistry class, heating up the charcoal could certainly do the trick assuming that it's not a gooey mess from decades of being soaked in oil and gas. The trick would be how hot you need to get it, although a propane torch would seem to be excessive.

How about just buying new activated carbon? It's used in numerous applications for water filtration and such, and from a quick search on the web, you can get a jug of the stuff for 10 or 20 bucks. Perhaps just do some research in terms of granule size, open up your charcoal canister, put new stuff in, and seal it back up?

-Bryan
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Re: Charcoal canister question

Post by davedecker4 » Sat Apr 27, 2019 3:20 pm

Here, here. There's nothing wrong with emissions equipment that doesn't actually decrease performance and economy for once.
And a small plastic canister doesn't add much weight
Dave Decker
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bartigue
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Re: Charcoal canister question

Post by bartigue » Sun Apr 28, 2019 7:09 am

You can refill it with fish tank charcoal and you can buy new ones - similar part on Alfa Romeo, BMW, Mercedes etc
-----------------------------------------------------------
Brad Artigue
1969, 1969, 1970, 1979, 1980, 1981, 1982, and 1982 124 Spiders
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atruscott
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Re: Charcoal canister question

Post by atruscott » Sun Apr 28, 2019 11:08 pm

I just cut the bottom third off mine, refill with fish tank charcoal, and silicone back together. Brad has never called me out during his concourse inspections ;)
1960 Autobianchi Bianchina Transformabile
1970 238 Camper OHV
1974 124 Wagon TC
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1975 124 Sport Coupe
1976 124 Sport Spider (The Racer)
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baltobernie2
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Re: Charcoal canister question

Post by baltobernie2 » Mon Apr 29, 2019 10:03 pm

The early plastic canisters can be refurbished. I used this Dremel saw to cut off the top:

Image

The foam can be replaced with McMaster Carr p/n 2195K101

Image

The empty canister:

Image

Replace with aquarium charcoal and the above-mentioned foam. The spring makes reattachment tricky; use straps, tape, etc. I used a "double bubble" epoxy specific to plastic applications.

Image
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Re: Charcoal canister question

Post by jseabolt » Sun May 05, 2019 7:51 am

If this is supposed to be a closed system, they how come when I top the fuel tank off in my 2003 Subaru off in May, and park it over the summer and start it in November, the fuel gauge indicates that it has lost several gallons of gas. Like 3 to 4 gallons. So where did the gasoline go? The canister only holds about 1 liter of charcoal. I would think at some point the tank has to vent if it builds up too much pressure. Or is there an issue with my fuel vapor recovery system? Maybe the charcoal is saturated and there is a safety valve that vents off excess tank pressure. But the CEL has never flashed a code saying there is something wrong with it.

There is one emission control device I do like that most people seem to do away with. The crankcase ventilation system. Some people end up routing the hose to a catch can. The reason I like this system is I don't like smelling oil vapors especially on my Spider and Yugo when the turbo winds up. This seems to create an excessive amount of blow-by and oil fumes enter the cabin.

Most people think this oil vapors condenses and cokes up the intake system. So they like to run the oil vapors into a plastic oil bottle poked full of holes with a rag in the bottom. Or even a hose directly to the ground.

Right now I have my crankcase vented directly into the AFM before the turbo.

Image

Unlike the way it was original designed where the hose feed into a port with a restricter (pinhole) before the throttle plate, the engine is now pulling a full and constant vaccum on the crankcase. Funny is that this is the ONLY car I own that does not burn oil. Even my Subaru has used a quart of oil every 3000 miles since the day I bought it new.

Now if you have oil puddling int the air cleaner where you need a catch can, then there definitely something wrong with the engine. Like a bad PVC valve.

I once looked at an 850 Spider and somehow had rigged up a garden hose to the crankcase vent and instead of oil fumes, it was blowing blue smoke out of the crankcase! That's one reason I decided not to buy it.
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Re: Charcoal canister question

Post by davedecker4 » Mon May 06, 2019 3:15 pm

jseabolt wrote:
Sun May 05, 2019 7:51 am
If this is supposed to be a closed system, they how come when I top the fuel tank off in my 2003 Subaru off in May, and park it over the summer and start it in November, the fuel gauge indicates that it has lost several gallons of gas. Like 3 to 4 gallons. So where did the gasoline go?
The neighbor kid's lawnmower ;)
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rridge
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Re: Charcoal canister question

Post by rridge » Mon May 06, 2019 4:37 pm

James,

I'll bet you are pulling less vacuum at the PCV port you made on the side of the AFM than at the stock location. People have the notion that there is a significant pressure loss through AFM. That's not true. The flapper door begins to open as the engine cranks and is almost fully open by the time the engine hits peak torque. The stock FI intake tract has several several feet of ductwork, more restrictive filter and a filter box to create pressure loss before incoming air passes the stock crankcase vent port.

I'd also argue that calling the Twin Cam set up "Positive Crankcase Ventilation" is a stretch. With no PCV valve to open and close the crankcase to a source of manifold vacuum its more passive than positive. It's almost the equivalent of running with an open vent but routing the end of the vent hose to the air filter box.

I doubt that the carbon canister hold more than a few ounces of fuel vapor. Like the crankcase vent, Fiat uses a passive system with no valve, at least on later Spiders. The carbon canister is always open to the atmosphere. Excess vapor goes out the vent.

It's also likely that the bulk of the long term fuel loss in storage is through the fuel hoses themselves, not the vent system. I've seen estimates that loss through older non-barrier hoses in a year's time can be a gallon or more, depending on how much pressure is typically carried in the fuel rail and the tank itself. Some vapor passes directly through the wall of the hose, some is absorbed by the fiber reinforcement and passed out at the end of the hose and some is lost through leakage at the hose to nipple connection. Spider's have an extra hose loss factor because a quart of fuel sits in the filler hose elbow at the tank port until the tank is almost empty.
Richard
'81 Turbo Spider
Rockville, MD
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