I have a 1979 F100 with a 351w swap in progress. I was wanting to know what to do with the line that goes from the vapor canister back along the frame rail? I removed the canister and now just have a line sitting there. I believe this connects to the tank at the rear so is there any worry about fuel traveling back up and leaking at the front?

Thanks,

Micah

 

You should really reconnect the vapor canister. There is no performance penalty and it keeps gas fumes from collecting under the hood and in the cab.

 

you could either hook your canister back up or plug the line. it shouldnt have liquid in it but that would keep dirt out of it

 

76supercab2-
I took it off because all the lines were disconnected when I got the truck, there was the metal line on the frame and the canister, nothing else. If I were to reconnect it what lines feed to it and from where? This was originally a 302 non-emissions truck. It is now 351W, holley DP (no vapor lines that I know of). Let me know if you need more info about the truck and its set up for reconnection.

Micah

 

Put the charcoal cannister back on and hook it up properly. There are a number of threads here on how to hook it up including some recently.

 

Mine has been disconnected since before I even owned it with no issues...unless you absolutely need it because of smog issues...you should just be able to bolck it off at the fitting on the tank...or at the very least put a check valve or similar valve on the end to allow pressure to escape without allowing dirt and other nasty little things back in.
-Chris

 

Plugging the line can cause problems with fuel delivery. Sometimes the gas cap or other leaks in the system will provide a vent tho.

The system is good for keeping that gas smell away from the vehicle. It also recovers the $$$ gas fumes that otherwise would drift away.

 

And all this time I thought I had to work to find $$$...now Ill just run around with a shop vac sucking up gas fumes to cash in on lol ...j/k.

I agree though...you should vent it somehow....but having the charcoal canister missing probably wont disable your truck...it is important to vent it somehow.
-Chris

 

I STRONGLY recommend everyone to reconnect the vapor canister if originally equipped.

The steel line is the FUEL RETURN HOSE. It runs all the way from the canister to the top of the gas tank (rear aft-of-axle steel 19.2 gallon gas tank...). FUEL, as in liquid itself, will be routed through the steel line if there is excessive fuel. If it's disconnected, you may experience fuel spillage. You don't want fuel spillage with today's gas prices.

Disconnecting it will also cause issues with vacuum/venting. The vapor canister also serve as the ventilation for the fuel system.

The rest go to the carburetor spacer plate and the bowl vent of the original carburetor. If applicable, one port goes to a secondary canister.

 

If equipped with the EEC system, the gas cap would be the sealed type. Won't be able to vent with that so you'll create a vacuum in the system...BOOM!

 

So by that logic...my truck has exploded then? Just trying to clarify it a bit...like I said before...mine has been dissconnected for quite some time...years...more like a decade or two....without issue. One has to remember that there was a time before emissions laws when vehicles ran just fine w/o all of the junk on them....like I said it is important to vent it but I still dont see why you guys are making it sound like removing it will be the end of a vehicle???
-Chris

 

No. If the EEC system has no way to vent, it will create vacuum and eventually find a weak spot and push its way through it. The EEC system was set up to vent the fumes through the canister which has charcoal in it to filter out the fumes.

The non-EEC system had a vented gas cap which where the fumes went out to the atmosphere, unfiltered.

It is not the end of the vehicle, but if you've done that...just as might go to a gas station and spray fuel all over the truck instead of in the gas tank.

It does not hurt engine performance to have the EEC system operational. You're saving fuel whenever possible. And you won't smell like a Exxon truck, either.

I know they didn't have then once. The trade-off was that they polluted more then.

 

The tank must have a vent someplace. If not it will created suction or pressure and cause you grief, including spraying fuel in your face when you take the cap off. On mine I used a small fuel filter on the end of the vent line to keep it open and clean.

 

If there is suction on your fuel tank, the OEM block mounted mechanical fuel pump will not last.

 

Ok,

I am not opposed to hooking it back up. However, I do need to know how to hook it up with my set-up. Nothing in my engine compartment is stock, the only vacuum lines I have are the dist. and the trans. The dist. runs off the carb and the trans. is off the manifold. The carb is a holley 4778-2, 700cfm mech. sec., manual choke, non emis. I don't have even have a pcv valve set-up as I am using pushin breathers on both valve covers. Also, no ports on the carb spacer since it is a solid 1" spacer. If it is a return line does that mean I could hook up a pres. regulator with relief and feed back to the tank with it?

Micah