Just had a question about my vacuum lines (I'm sure you guys get a lot of them)

I have these two canisters on the passenger side with 90% of the vacuum lines coming out of it. When the engine is running, the lines have no vacuum whatsoever. (one upper one lower canister)



Lines that go to them are all from the carb (sans dist vac advance), and one from water neck



The largest ports on the carb (Front and rear) also have lines going to them, but I had them off for this.


So the question is, what are these canisters? And are these lines really vacuum lines? There are no lines heading to the manifold from there, so there is no source of vacuum.


Thanks
Jameson

 

This is part of you evaporative emissions control system. Most of the lines are vacuum lines. There should also be a line that goes to the fuel tank(s).
Here is an illustration from the Ford parts catalog to give you an idea of how its set up.
Also, some set ups used dual charcoal canisters. Sounds like that's what you have.
Click on the .pdf link to view.

 

So i should get vacuum to those lines?

The line going to the tank was not attached when i bought it. I am not using any emissions controls (removed a.i.r pump, egr, ect.), so could i take those canisters out?

 

If you aren't running any emission equipment, you could remove them.
I'd save them just incase you have to install them again in the future.

 

If memory serves me correctly, the purge valve on top of the canister is sourced from ported vacuum. If that's the case, you won't have vacuum anywhere at idle in the first place.

Most of the lines in and out of the canister are evaporative lines and not vacuum lines. You'll have one from the tank (tank fumes) and one from the carburetor (fuel bowl fumes). The output of the purge valve dumps to the air cleaner to get burned.

 

There is a separate set of vac lines that source from the rear of the intake. They go to a canister under the drivers side fender, and provide vac for the cruise control and the power breaks.


So if I take the charcoal canisters out, and remove the emissions lines going to and from the carb, will I need to plug all the openings on the carb?


Thanks
Jameson

 

Yes if you choose not to deal the the charcoal canisters, you would want to plug the big tubes that comes out of the float bowls. Some will say "No, you can't plug those because the float bowls need to be vented" Yes, they need to be vented but that's not looking at the whole picture and why the factory setup is actually there. The float bowls are already vented into the air cleaner through the two vertical tubes that come out of the carburator.

If you don't cap them: A. The gas in the bowls will evaporate faster. B. You are more likely to get water/condensation in the float bowls. C. Since the bowls are already vented into the air cleaner it is possible that you may pull a draft through the float bowls and get dust/dirt in the carb.

Out of curiosisty where is that vacuum line running, the aluminum one that comes out directly above the choke cap? That is just a fresh air tube and does not pull a vacuum.

 

The one in front of the ID tag goes to the water neck. The other one (larger of the two) goes to the top charcoal canister

 

Seems easy enough to get rid of this system, but what do ya want to do with the vent tube coming from the fuel tank if you get rid of the evap canister?

 

Coming off the bent metal line from the tank, is a length of rubber tubing. On the end of that, there is a plug. The truck was that way when I bought it.

 

Is there another vent to the tank, cause id hate to get rid of one of the fuel tank vents if there wasn't another one. Ill have to do some investigatinh

 

You can leave that one uncapped. There is a check valve in the fuel tank. If you do cap it be sure to change your fuel cap to a vented cap or you'll start to have fuel delivery issues.
Trucks with the charcoal canister vented the tank through the system so they used a non-vented cap.

 

Oh I didn't realize that mattered. Since I don't have vented caps, should I uncap the fuel vapor line?