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It is a vent for the gas fumes to the charcoal canister under the battery.
The part in/on the tank is a roll over valve. If you end up on your lid it closes off so fuel will not come out.
There is the short rubber hose to the metal line that runs on the frame cross member at the rear of the cab over to the right side frame rail to the front.
Now if you had dule tanks when that line got to the right frame rail it Teed in with the rear tank then to the front and 2 canisters.
Dave - - - -
It is a vent for the gas fumes to the charcoal canister under the battery.
The part in/on the tank is a roll over valve. If you end up on your lid it closes off so fuel will not come out.
There is the short rubber hose to the metal line that runs on the frame cross member at the rear of the cab over to the right side frame rail to the front.
Now if you had dule tanks when that line got to the right frame rail it Teed in with the rear tank then to the front and 2 canisters.
Dave - - - -
Thanks Dave...that's super helpful. I have a single tank on my 85 and the metal tube that ran along the cab and up the frame is basically totally corroded away.
Normally, it should go from the top of the tank, along the cab up the rail to the charcoal canister under the battery. Does it end there or where does it go from there? Up to the carb?
(I had a mystery rotted tube hanging off of the side of the carb as well, I assumed it was all part of the same system.)
Also, I'm guessing that me having capped off the top of the tank and the tip that goes into the carb capped off is probably not ideal, right?
I can definitely post pictures if that makes this easier, I just have to find them.
I don't see any real issue with capping the tank side as the gas cap should be vented so will let pressure out and in as needed.
Not knowing what port you capped on the carb it is hard to say what will happen but in most cases you should also be ok.
This is how my 81 300 six is hooked up.
As I said the vent is for fumes and is collected in the canister. There is a hose from the canister to the carb float bowl so the fumes from it go to the canister.
Now IIRC there is a Tee in the line to the carb bowl and this gets hooked to the top of the PCV as it has 2 hose connections. The lower one connects the PCV to the intake to pull vapors from the motors crank case.
There is also some other things like a solenoid on some trucks to only pull fumes at certain times when the motor is running but I am not worried about that ..... at this time but I don't think it will be an issues on my truck.
Also if you have the vacuum hose routing sticker on your radiator support it should list how that gets plumbed. This is from my parts truck with duel tanks as I added the 2nd tank to my flare side.
You can see the 2 canisters at the top left of the sticker and a hose running to a PV (purge valve) I am not using that PV as I don't have one.
link to a larger picture open it and click picture to make it larger. http://cars.grantskingdom.com/index....0160606_165929
Dave ----
I did a little further inspecting last night and followed the rotted vent-line from the tank all the way into the charcoal box. It's totally corroded and would definitely need to be replaced if I do take off the tank-cap that I have in place.
I suppose I'll have to cap off the other end that leads into the charcoal box as well?
Here is a photo of the mystery tube that I THOUGHT came directly from the tank into the carb.
Any ideas what this is and if it's necessary to have connected?
Is there any way that finding the source of this would make my 85 F150 run a bit smoother?
for what it's worth...this is the rotted tube that I found hanging off of the carb. It's a metal pipe that is connected to a rubber line which connects to a bottom spout on the carb.
here you can see where I capped it off, I'm holding the tube close to where it was connected with a rubber hose, RUBBER HOSE NOT PICTURED.
Sometimes there is a CAL sticker on the valve cover, sometime on the drivers side door pillar.
The build/manufacture date is usually on a sticker in the drivers side door pillar.
I did a little further inspecting last night and followed the rotted vent-line from the tank all the way into the charcoal box. It's totally corroded and would definitely need to be replaced if I do take off the tank-cap that I have in place.
I suppose I'll have to cap off the other end that leads into the charcoal box as well?
Here is a photo of the mystery tube that I THOUGHT came directly from the tank into the carb.
Any ideas what this is and if it's necessary to have connected?
Is there any way that finding the source of this would make my 85 F150 run a bit smoother?
for what it's worth...this is the rotted tube that I found hanging off of the carb. It's a metal pipe that is connected to a rubber line which connects to a bottom spout on the carb.
here you can see where I capped it off, I'm holding the tube close to where it was connected with a rubber hose, RUBBER HOSE NOT PICTURED.
Ok as said that metal line & hose hooked to that port on the carb to pull in filtered air. The line went to the bottom of the stock exh manifold and out the top and the line with insulation on it up to the choke housing on the carb.
Now in the picture I see a line to the choke does it go to the exh manifold? If so then it would be just the line in your hand needs to be hooked up, easier said then done.
Dave ----
