Evaporative fuel system

[cigar-]

I have a 1971 C10 that I am working on. In the process I noticed a black plastic cannister mounted on the core support passenger side. Someonetold me this the "evaporative fuel module". After a bit of noodling around I see there are connections to the fuel system.

Right now only one inlet on top has something connected to the cannister. The other two fitting have a remnant of fule line hose attached. Does anyone know how this system works? Is it necessary to have all of the fittings connected?

My truck is a California vehcle and is outside of the smog requirements. When I bought it the truck ran ok. Now that I am putting in a new motor and fixing other problems, I'd like to know if I can leave this thing disconnected. Also....does the other two fittings being open to the atmosphere adversely affect the truck's performance.

Thanks in adavnce for any and all help.

Michael

[BigRed76]

Yes that is the charcoal canister. Seeing how you are outside of smog requirements it is not necessary for you to have it connected. I'm not 100% sure on this, but I believe the canister has one line going to the fuel tank and another line that goes to a port on the carburetor. Having the charcoal canister disconnected won't affect engine performance, it will just allow the evaporative emissions from the fuel tank to vent into the atmosphere like we did for 70+ years

Also noticed this is your first post...

[54blackhornet]

One hose goes to port on front of carb, if its a QJet, the other hose goes to line connected to drivers side PCV valve. It also has a line going under vehicle , along frame to fuel tank on pass side of tank, look behind seat on pass side and you will see the connections. Hope this points you in right direction. Also you need a non vented gas cap if you put it back to stock. You can use a later style canister if original one is cracked.
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[tlcrz1972]

54black hornet is correct on the hose connections.

Install it like it's supposed to be, then you don't have any concerns about it.
Yes to make it work correctly it does need a functioning charcoal canister. But like you said it is out of the smog check age.
I have mine set up as it should be from the factory and have had no gas fume problems ever.

[cigar-]

Thank you to all for the helpful and speedy replies. I am not going to a stock carb. In fact I was planning on an Edelbrock 1406 four barrel with electric choke. I have that on two street rods and they run fine.That way I have new carb....not an old rebuilt one that will possibly provide me problems.

I look forward to posting more threads and possibly contributing to some.

[cdowns]

the main thing alot of guys do wrong is that hose from the gastank // they just close it shut but do not realize it is the vent for the gas tank// when eliminating that cannister i always rerouted the gastank hose back along the frame rail in back of the cab to allow venting and not getting fumes in the cab

[engineer_gregh]

tlcrz1972 can you share more on how your lines are connected. My 71 makes my garage smell like gas. I'm not leaking any fuel but the canister is not connected and I'm thinking that is the problem. thanks.