Ozz1967

iTrader: (4)

Hey guys,

The green top vacuum sensor thing does what exactly?

84 T/A with CC Qjet.

This thing goes from to both the vacuum switch, also pictured and the charcoal canister.

I'm blocking off my charcoal canister because I"m getting fuel pulled back up the lines and that's not good. Caused me all kinds of problems a few years ago.

I've already removed and plugged all the other lines coming from the charcoal canister so If I don't need it, I"m thinking of pulling it and moving my secondary fan temp switch out of my thermostat housing...or I'll just plug it. Heck,I just might leave it there for now.

No emissions for me since I'm out of state and "drive" it less than "60 days" per year. muhaha




Any help would be very appreciated.

Rolling Thunder

Once upon a time that vacuum switch used to control your thermac valve. I cant really see from the picture if you have the factory air cleaner but the thermac valve is a valve in the air cleaner that would switch between sucking hot air off the exhaust manifold when cold or cooler air from the snorkel when warmed up.

gearhead141

The component with the green top is a thermal control valve. The two hoses coming off of it go to (1) the cannister control valve ( the second pic you show), and (2) the charcoal canister itself. If you want to do away with the entire system, this valve is part of it.

Ozz1967

iTrader: (4)

Well, im still getting fuel pulled up through the charcoal canister for some reason, its filling up the canister control valve and that's not good for many reasons. Mainly because I can't figure out why. This also happened several years ago and i disconnected it then. I thought putting on a new canister control valve would fix it bit it didn't.

Knowing I can disconnect it without hirting anything really eases my mind

gearhead141

I did notice that your Canister Control Valve is sitting on the fender well. I have never seen one there before. Not that it has anything to do with the operation, I've just never seen one way over there. Anyway, if you have everything plumbing wise connected correctly, then it could be that the tank pressure control valve is leaking or inop. That thermal switch is supposed to cut off canister purge below 170F. If you have questions concerning hose connection and routing let us know.

Ozz1967

iTrader: (4)

I extended the hoses over to get it off the top of the motor, just trying to make it more visually appealing.

In 2010, my car started running super lean, bucking and cutting out. I couldn't figure it out. I took it to a specialist, old school car guy our car club recommended since no one else knew anythingt about carbs. He eventually pulled the carb and found black bits all clogging up the venturies and other tubes in the carb. Then he found gasoline filling up the canister control switch and in the 3/8" vacuum lines. The carb was pulling gas up through the canister and into the carb. The black bits were the tiny charcoal pieces being sucked up into the carb.

He disconnected the canister and said I needed a new control valve. This past fall when I parked the car I finally got a new control valve and hooked everything back up.

I used the diagrams i found here on the site for proper vacuum hose routing.

I ran it 3 times this winter, 30 min or so at a time once a month just to keep the car running and checked, and could see no visual queues that my issue was coming back. At least until I drove the car for about 30 min the other day when it was nice out. I ran it pretty hard and checked it when I got hom and once again has fuel in the control valve and starting to come up the vacuum lines.

I panicked and I'm now saying screw it. I don't want to risk clogging up the carb again since it's been dialed in by the shop so I am pulling all the lines from the canister and plugging all the ports on the carb.

the only thing running to the carb now are the PCV valve, the brake booster and the otehr vacuum line that goes to the vent controls. Everything else is capped.

sofakingdom

iTrader: (1)

It is NOT related to the Thermac system. That system is entirely self-contained.

It is the canister purge control valve. It's a thermal vacuum switch; opens, and sends vacuum to the purge valve itself (funky thing with a bunch of lines hanging in front of the intake) when the engine warms up enough. 150° or some such.

More likely the reason you have raw fuel in the canister, is a bad "UFO" (at the rear of the car, just inboard of the driver's side rear wheel).

FRMULA88

there is a vent line from the fuel tank to the canister. the fuel vapors are stored in the charcoal canister until the engine is running then the vapors are let into the carb to vent the tank and burn off the fumes. the check valve works off engine vucuum/ temp.

engine on vacuum applies valve open at set temp. .. engine off valve closed vapors stored in canister and lines

it is an emissions control device prior to this the fuel tank / carburetor vented to the atmosphere. the automakers and EPA decided this was not a great idea with millions of cars on the road emitting gasoline fumes.

a race car that is parked... not a big deal. my tank is vented with a one-way valve draws air in does not let fuel out.. my carb bowls may run dry when parked for the season if I forget to cap the vent lines but we are talking 6-8 oz of fuel when that gone. fumes cannot get past a closed needle and seat at that point.

the check valve located at the rear of the car coming off the fuel tank is no longer produced, if yours is bad you will have to find a NOS or salvage yard part,

Ozz1967

iTrader: (4)

Sweet! Aliens!

What does this thing look like so I know what I'm eyeballing? Its not the white-ish vent thing hanging down from the tank is it?

Ozz1967

iTrader: (4)

is it possible to put this checkvalve that you run on my factory set up?

As it stands right now, I've disconnected everything but one of the 3/8 lines going to the green top sensor and plugged off all associated vacuum lines and ports.

FRMULA88

there is nothing "factory setup" about my fuel system except for the sending unit for the fuel gage.

naf

iTrader: (7)

The ufo is about 1 to 1 1/2 inches in diameter and mounted near the tank on a bracket. It has one rubber hose going from it to the tank. You should be able to provide a few psi of air to either the feed or return fuel line and hear it vent (with gas cap tight). It is designed to allow a small amount of over pressure to develop within the system. This over pressure forces vapors into the canister. The ufo releases excess pressure that could otherwise damage the purge system.

You can also remove all of the hoses and associated TVS for the canister if you desire. Once removed you may want to install a vented gas cap.

Ozz1967

iTrader: (4)

I think for now I'm going to simply disconnect and plug the canister from the motor. I'm going to look into the UFO check-valve thing on the back of the car.

Is it that the UFO thing isn't venting and is instead forcing fuel up the line? IS that what's causing this issue?

naf

iTrader: (7)

If the tank were not venting, I would 'think' that the only thing being forced up the charcoal canister line would be vapor. But two options come to mind:

Enough vapor is forced into the canister to allow a significant amount of fuel to condense or

fuel is being forced up the fuel lines and overflowing the carb vent bowl into the canister.

Having no experience with this condition and a too dim memory of how the vent line ties into the tank, I would have to leave the explanation to others.

Ozz1967

iTrader: (4)

Ok, I'm going to just leave it disconnected then and not worry about it for now. It was disconnected for the better part of 3 years and never caused any problems. I was just hoping I could maybe actually get it fixed.

Time for a 4th gen tank maybe? hehe