Poly tank -> OEM Evap Emissions (1 Viewer)

[CruisinGA]

almost 20 years ago I installed a poly tank in my FJ40 and found that the vapor separator (on my 10/73 mounted next to the filler neck) and check valve were both broken. Charcoal canister long gone.
I am currently replacing the poly tank with an OEM tank. What's the "best/simplest" way to set up the vents? With the 1/2" vent line to the filler neck, are the other vents really needed- can they be plugged?

 

[micruz60]

I believe the 'best' way is to get back to stock configuration.

I also replaced the OEM tank with a poly one waaay back in 2000, and it needs some attention with fumes accumulating in the cabin- probably a fresh charcoal canister and lines to / from vapor separator.

 

[ducktapeguy]

The tank will build up pressure under normal use. If you seal off the vents the tank will bulge and eventually you'll get a gas smell in the cabin as the vapors work their way through any opening. You could get a vented gas cap (or just have a old cracked seal like mine had), but you'll still get a gas smell, just outside the cabin. The best way is to deal with it is to get the charcoal canister hooked up again.

My vapor cannister ports kept breaking so I just replaced it with an aluminum air manifold and brass fittings, it's been working fine and I don't have to worry about the ports breaking off again. Those all collect into one line that goes through a check valve and eventually into your charcoal cannister where they'll get burned up in the engine.

 

[CruisinGA]

Thanks @ducktapeguy just ordered an aluminum manifold and fittings to re-create a more durable vapor canister. Planning to route to an afternmarket charcoal canister and from there to intake of the carb to have slight vacuum.

 

[ducktapeguy]

I did a lot of troubleshooting to get rid of the fuel smell in my cruiser. It was so bad I thought turning on the radio would cause the 40 to explode.

From what I remember, the check valve will keep a constant pressure in the tank, <1psi, but it's enough to be noticeable when you remove the cap. The charcoal cannister is connected to the VSV, which is supposed to open the vacuum line to the manifold at certain times and will suck all those fumes out. I want to say only at WOT and when the manifold vac is below (or above, I can't remember) a certain reading.

If your VSV isn't working it's controlled by the "computer" box under the dash near the fuse box, it's known for breaking some solder joints. If you look close in the bottom picture you might be able to see it. After fixing all those problems plus a bunch of others, no more gas smell anywhere. I can even park in the garage without worrying about getting blown up.

 

[CruisinGA]

Thanks for the info! I ordered an OEM check valve and put together a new manifold from Mcmaster parts.
I still have the computer under the dash, but my VSV is long gone, I'll have to figure something else out since I don't want to apply manifold vacuum directly to the evap system.