Fuel charcoal Canister

[kameltoes2015]

I am in the process installing my fuel tank under the bed. The question I have is do I need to install a Fuel Vapor Canister? This would be going on a 1949 Chevy truck

[1project2many]

The cannister isn't required but if you have an appropriate tank and can connect the can, it will reduce the odds your truck stinks like gasoline on a hot summer day.

[kameltoes2015]

Thanks for the reply.

[mr48chev]

He pretty well nailed it in post 1 if you have a newer style tank with the vent hose on it the canister tucked up front somewhere helps keep the fumes to a minimum. It also solves the tank venting problem that a lot of guys run into. A bit of searching in the pick a parts yard might get you a smaller size canister that is easier to tuck away possibly off a mid 80's GM car with a carb that had a transverse engine.

[kameltoes2015]

Thank, my tank came from Tanks, Inc. That was going to be my next question, what canister is recommended.

[roger55]

If you put a charcoal cannister on it, you have to figure out how to purge it when the engine is running. If it's not purged, it can be dangerous.

[Coupeguy2001]

You can get the purge solenoid from the donor car, and hook up a 12 volt timer relay that turns off after about 1 minute.
The problem here is that usually anything that had a cannister had a computer with a purge programmed into the engine computer.
Maybe you could find an electronic timer diagram on the internet and build your own from the instructions.

The next obstacle is that you have to have a vent valve that would let air in as the vacuum in the manifold sucked it out.
The timer could open the purge solenoid and the vent valve at the same time.

Today's cars run a program that cycles the purge solenoid about 20 times a second so the engine does not see a big vacuum leak. You would be essentially designing your own system, so you would understand why you have a high idle when you first start up the truck.
Parts typically wouldn't run over $15

[mr48chev]

Pre computer canisters like one off about a 75 GM most anything just have a hose that runs back to the carb. It shouldn't be hard to duplicate that.

You could probably run a vent hose over and up in the stake pocket a ways and maybe put a filter of some sort on it to keep the dirt out. A plastic inline fuel filter would probably do the trick there. It needs to be up high enough so that no matter what angle the truck sits at it can't overflow. I remember those old drop the license plate and fill the tank cars out of the late 50's and early 60's loosing gas when the tank was full and the car was parked nose up on a somewhat steep incline.