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I have an 82 f100 with a 302 auto tranny and a motorcraft carb i think its a 2100 i think, the tag is missing and im just gussing from pics. There is a large spout/nipple on the front towards the top of the carb that looks like it should be connested to some sort of hose. It's looks to have an i.d. of about 1/4". Is this something that needs to be connected or does it need to be plugged. The smog pump and all that stuff is gone and plugged off could it go to that or what? Thanks for the help in advance.
Is that the white plastic box below the battery that seems like it does nothing...guess it does have a purpose. What would be the reprocutions of leaving it unhooked?
That's the one. Leaving it unhooked is technically bad for the environment, but it's not going to hurt anything as far as your truck goes. You're definitely not the only one running that way and most people's purge valve on top of the canister has gone bad by now anyway. The purpose of that setup is to collect evaporative fumes from the gas tank and carburetor fuel bowl and collect them in an active-charcoal canister, and periodically introduce them into the combustion stream to be re-burned.
The purpose of that setup is to collect evaporative fumes from the gas tank and carburetor fuel bowl and collect them in an active-charcoal canister, and periodically introduce them into the combustion stream to be re-burned.
fmc400, the one on my 1985 F150 has been unhooked for years now, and I always wondered why I always smelled gas under my hood even though I don't have any leaks. When I changed from the feedback carb to a conventional carb setup, I didn't know what to do with it, because it was originally purged electronically by the EEC-IV computer, which is long gone.
I would like to get this system working again, so I got another canister and purge valve from a (1979) conventional carburetor setup. The purge valve is located on top of the canister, and it has 4 lines going to it. Will you check this and see if this is correct?
1- One line goes to the vent on the gas tank,
2- The largest line goes to the vent on the carburetor
3- One line goes to a thermal vacuum switch, and from there to ported vacuum, (purge signal)
4- and the small, narrow line hooks to the smaller top port of the PCV valve (for purging).
Sorry Lariat; I didn't see this post right away. You're correct that there are four connections - the fuel tank (for gasoline fumes in the tank), the carburetor (for gasoline fumes in the fuel bowl), ported vacuum downstream of a ported vacuum switch (purge signal), and a dump line to reburn collected fumes. As far as which size line goes where, I'm afraid I can't say for sure because mine is long gone as well.
I do have one possible correction - for number 4, the top port of the PCV valve is a manifold vacuum signal. In my experience I have seen the dump line run to the top of the carburetor - be it the air horn itself, or the air cleaner. I haven't seen it routed directly to manifold vacuum as you have described. That doesn't mean Ford never did it that way though. Either way, the fumes get back into the combustion mix.