Evaporative Emission controls (1 Viewer)

[FJ40fiji]

On my 72 FJ40, There is what I assume to be a charcol canister on the inside of my front fender, it is attached to a device by hard lines which has long been disconnected that at one time appears it would have had vacume lines running to it. Also from the canister are hard lines going to another canister in the center section of my bench seat which is in turn connected to my fuel tank.
Question is, other than needing to cap any ports on my fuel tank, do I need to do anything special when I remove all of this? Is it neccesary for controling fumes in the cab if I put a hard top on the truck? And lastly, would it really make a difference environmentally if hooked it all back up? I am smog exempt so I don't have to have it, and the canister is probably no longer functional.
Also there is a small rectangular device on the inside of the passenger side fender just above the battery with three electrical terminals on it. The electrical system on this rig has been "replaced" by a PO, and I am not sure what this is. I would guess that it may have been like a main bus or something before. It hasn't been connected in a long time, just don't know if it is something I should hold on to. I'll likely toss it, unless one of you guys needs it.

 

[65swb45]

The piece above your battery is most likely the relay for the horn.

As far as the gas tank goes, a properly routed charcoal canister is a good thing. Rather than letting vapor pressure build up, if you can capture it, condense what can be condensed thru the canister to be returned to the tank, and pass on the true vapors into the carb to be burned, that would be a good thing.

Unfortunately, the 72 emissions system bears little resemblance to what I just described.

GL

Mark

 

[FJ40fiji]

Poser, you got an opinion on this? You seem to have alot of answers.

 

[Mr. Toad]

Question is, [1] other than needing to cap any ports on my fuel tank, do I need to do anything special when I remove all of this? [2] Is it neccesary for controling fumes in the cab if I put a hard top on the truck? [3] And lastly, would it really make a difference environmentally if hooked it all back up? I am smog exempt so I don't have to have it, and the canister is probably no longer functional.

1)

Generally, no. But read on.​

2)

Not necessary, but very helpful. Your fuel heats up due to drivetrain/exhaust heat coming up through the floor, not to mention general sloshing around. As your fuel heats up, it creates more hydrocarbon vapor. The vapor is a gas. The more gas there is, the higher the pressure inside your tank. The more pressure, the more it tries to vent through one of the hoses or hose junctions in the cab. One likely place for a leak is the large rubber connector between tank and filler pipe.

Your evaporative emission system reduces the pressure by applying manifold vacuum to the fuel system when your cruiser travels above certain speeds. This not only reduces the likelihood of fumes inside your hardtop (by reducing gasseous pressure in the fuel system), but it also burns those vaporized hydrocarbons in your engine.
​

3)

Yes, if it all works. Not only does the evaporative emissions system burn hydrocarbon gas produced in your fuel tank, but it does something else too. It controls your throttle positioner (TP). Without a TP, your carb would try to completely close itself to air when you decelerate. This causes an extra-rich condition in the engine. Since there's not enough oxygen to completely burn the fuel, you spew unburnt hydrocarbons out the tailpipe. Ever wonder why the truck stinks when you slow down with it in gear?

The TP prevents your carb from completely shutting down during deceleration. Thus, your fuel burns more completely, you emit less unburned hydrocarbons, and the truck and your surroundings stink less.​

Does your TP work now? (It works if your cruiser holds a higher idle when decelerating, then drops off at about 10 mph) If it works, then it's likely that your evaporative emissions system is probably working too. If it doesn't then you're pretty lucky because the 1972 system is very simple.

 

[FJ40fiji]

Well, it's actually running a 1976 2F, and a weber carb. The F intake is still on there and there is a vacume port that points right at the box type component that is routed to the charcol canister. Is that where it should be hooked up, or did it originally go to the carb itself? If it actually improves the way the truck runs I definatly want to hook it back up and see what it does.

 

[Mr. Toad]

Well, it's actually running a 1976 2F, and a weber carb. The F intake is still on there and there is a vacume port that points right at the box type component that is routed to the charcol canister. Is that where it should be hooked up, or did it originally go to the carb itself? If it actually improves the way the truck runs I definatly want to hook it back up and see what it does.

That sounds like the right vacuum port on your intake manifold. However, I don't know if it'll make your cruiser run any better, though it may make it pollute less. I know nothing about Weber carbs. Does it even have a throttle positioner?

If I were you--and if I could verify that the computer and vacuum mechanisms still work--I'd hook up the system so that at least it draws gasses from the fuel tank system. Maybe keep the fumes down inside the hardtop.

 

[65swb45]

I would NOT hook up any port on the intake directly to the evap system. Evap should be drawn in through a metered system, or thru a point that is not likely to produce an effect on the overall air-fuel mix ratio.

On 71 cruisers for instance, there was a 1/4" nipple sticking down from the air cleaner midway between the canister and the carb that would be an excellent spot to introduce fuel vapors into the intake system.

Mark A.

 

[Mr. Toad]

I would NOT hook up any port on the intake directly to the evap system. Evap should be drawn in through a metered system, or thru a point that is not likely to produce an effect on the overall air-fuel mix ratio.

On 71 cruisers for instance, there was a 1/4" nipple sticking down from the air cleaner midway between the canister and the carb that would be an excellent spot to introduce fuel vapors into the intake system.

Good point. I may have been assuming more than I should have: i.e. that it's general knowledge that the evap. emissions system is a system, and that it includes a vacuum control valve, computer, speed sensor, vacuum source, throttle positioner, fuel system, etc.

Direct connecting the charcoal canister to the manifold vacuum port is not likely to do anything good. I suppose it could be direct-routed to the air cleaner, but I don't know if the air cleaner flow could produce enough vacuum to overcome the check-valve resistance on the fuel-tank side of the canister.

Nevertheless, 40ozFJ's 1972 emissions system was designed to introduce the fuel vapors from the charcoal-canister/fuel-tank into the intake manifold via the computer-controlled Vacuum Switching Valve.

So if you're going to try to hook up the evaporative emissions system, don't expect it to work if it is hooked up to the air cleaner housing instead of manifold vacuum.

 

[Mickey Plunkett]

I removed the charcoal canister from my 79 and was thinking of connecting the vent tube from the tank directly to the air cleaner. That should provide enough vacuum to keep any pressure from building in the tank and keep the fumes inside the air filter. Anybody see a problem with that approach?

 

[FJ40Jim]

Yes, the problem will come on a hot day after a fillup. The tank may actually puke some liquid gas, which will then be sloshing around inside the air cleaner and saturating the paper element. A carb backfire on the naxt starting attempt and things get ugly.

If the vehicle has to be operated without the stock canister, make a mini canister by running the tank vapor line through one or more disposable fuel filters. Vent it to atmospher as high as possible under the hood. Keep the vent outlet away from spark, exhaust heat and the heaterbox.

 

[Mr. Toad]

I removed the charcoal canister from my 79

Porque?

 

[PabloCruise]

Porque?

I believe the correct spelling is "pork"

Or do you mean Por Que?

 

[Mr. Toad]

I believe the correct spelling is "pork"

Or do you mean Por Que?

Porque.

 

[PabloCruise]

Porque.

DAMMIT!

 

[Mr. Toad]

DAMMIT!

But I had to look it up. Especially since it came from someone called "Pablo"

 

[FJ40fiji]

Anybody out there scrapped the system all together with good , bad or indifferent results? I never have enough cash to fill it up all the way in summer anyhow!

 

[DSRTRDR]

Why not running as designed? That's what I do, works fine. That plumbing in the middle seat is certainly something special