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  1. #1

    Default Tank vent tube to manifold?

    I was reading through the posts and read a thread on the charcoal can. Mine is deleted. The tube vents to the atmosphere. Most likely not a smart idea but curious as to the effects of connecting the vent tube to the intake manifold and using a vented gas cap? Would I run rich, blow myself up, or find a few hidden ponies? Just curious as to your thoughts or if someone had the balls to do it. Haha.

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  2. #2

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    No one has any thoughts on this?

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  3. #3

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    I'll give it a shot.

    As I understand the system, the fuel tank vents to the charcoal cannister. Fumes are contained in the charcoal cannister until the engine is running, and the EEC commands the purge valve to open, allowing the fumes to be sucked into the intake manifold. Read somewhere that when this happens the EEC slightly leans the air/fuel mixture to compensate for the fuel rich air being drawn from the charcoal cannister.

    My guess is that if you hook the vent tube directly to the intake manifold you'll end up running rich. But then again, it's just a guess.

  4. #4

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    Thanks for the input man. It's something thats been on my mind. I wonder if you could close the gap on the spark plugs to compensate. Also it would probably affect my sd as opposed to a maf car im sure. Id be drawing un metered air into the vented gas cap im assuming.

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  5. #5

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    Maybe hook the oil fill baffle to a vacuume line under the manifold and hook the vent tube to the vacuume line on the throttle body or a nipple on the cai that way the iac can read it.

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    Last edited by Jackthemind; 04-24-2017 at 03:22 PM.

  6. #6
    FEP Member Mgino757's Avatar
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    My tank vent was capped off when I got my 85. I found the parts necessary to run the evap system semi-properly. The parts you'll need to make yours work properly will be the charcoal canister, canister purge valve, red vacuum restrictor, blue vacuum restrictor, a brown/black vacuum delay valve, a ported or EGR vacuum source from the carburetor and what ever amount of vacuum tubing needed to make all your connections. Plugging the tank vent straight into manifold vacuum will cause a higher than necessary idle, hard starting, and a lean running condition.

    What fox are we talking here? 86? 85? 84? etc?

    refer to this thread. http://vb.foureyedpride.com/showthre...vap-components

    Quote Originally Posted by Jackthemind View Post
    Maybe hook the oil fill baffle to a vacuume line under the manifold and hook the vent tube to the vacuume line on the throttle body or a nipple on the cai that way the iac can read it.

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    Sounds like you have an 86. Don't hook up the vapor vent to the crank case. Hook up the oil fill baffle to the correct fitting on the throttle body. Your PCV valve should be connected to manifold vacuum.

    In your case, this is how you need to connect your evap system.

    http://www.veryuseful.com/mustang/te...uumDiagram.jpg
    Last edited by Mgino757; 04-24-2017 at 06:21 PM.
    1985 Mustang GT conv. modified 4180C, Weiand Street Warrior intake, equal length headers, true dual exhaust, 3.55:1 8.8'' rear end, 2003 V6 T5, Ford Racing 10.5" clutch.

    1998 Mustang GT auto. PI swapped. Daily beater

  7. #7

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    I deleted all of my emissions and canister. My tank ventilation goes to the atmosphere much like an old school draft tube. Im not looking to put it back on just see how it would effect running conditions to hook the vent tube to the manifold or cai with a ventilated gas cap.

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  8. #8

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    I appreciate the information though, it will still help others with research.

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  9. #9

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    I was thinking it could be somewhat of a substitute for larger injectors.

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  10. #10

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    Quote Originally Posted by av8vito View Post
    I'll give it a shot.

    As I understand the system, the fuel tank vents to the charcoal cannister. Fumes are contained in the charcoal cannister until the engine is running, and the EEC commands the purge valve to open, allowing the fumes to be sucked into the intake manifold. Read somewhere that when this happens the EEC slightly leans the air/fuel mixture to compensate for the fuel rich air being drawn from the charcoal cannister.

    My guess is that if you hook the vent tube directly to the intake manifold you'll end up running rich. But then again, it's just a guess.
    Just wondering if you have tried this yet?

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  11. #11

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    No. What little I know of the system comes from researching why my fuel tank had pressure build up. Ended up being a failed Cannister Purge Solenoid. During my research, ran across the information I passed on. The fuel vent / canister / purge valve system doesn't cost any power, so I just fixed it. Got rid of some gasoline smell around the charcoal canister, solved the fuel tank pressure problem, and kept me smog check legal should I ever need to go through that.

  12. #12

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    Im picking up a cai with a vacuum nipple tommorrow. Then a vented gas cap. I also bought new spark plugs. What should I gap them to in your opinion with doing this?

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  13. #13

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    The factory cap -is- vented, with a one-way valve to permit air into the tank. The vapor valve in the tank has a bit
    of resistance, so I doubt you'll get any appreciable enrichment from such a setup. But venting tank vapors into the
    intake tube does seem like a good way for something to make a loud noise, sooner or later... ;-)
    Cheers,
    Jeff Cook

    '85 GT Hatch, 5-speed T-Top, Eibachs, Konis, & ARE 5-Spokes ... '85 GT Vert, CFI/AOD, all factory...
    '79 Fairmont StaWag, 5.0, 62K original miles ... '04 Azure Blue 40th Anny Mach 1, 37K original miles...
    2012 F150 S-Crew 4x4 5.0 "Blue Coyote"... 65 coupe, 289 auto, Pony interior ... '67 coupe 6-cyl 4-speed ...
    '68 Vert, Mexican block 307 4-speed... '71 Datsun 510 ...
    And a 1-of-328 Deep Blue Pearl 2003 Marauder 4.6 DOHC, J-Mod, 4.10s and Lidio tune

  14. #14

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    Bad or good loud noise? Haha.

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