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fuel tank evap canisters?

Discussion in 'Off Topic Threads' started by Steve NJ, Jun 28, 2009.

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  1. Steve NJ

    Steve NJ Member

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    Jan 29, 1998
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    I got a code of P0440 for same problem. Checked for leaks in EVAP vac system, changed a few hoses light just came back on after 3 days. Going to order the valve tomorrow and I'll let you know the results after that. BYW its for my Step Daughter's 99 VW Jetta.
     
  2. Conn. Man

    Conn. Man Member

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    Ck the fuel cap also,or just replace it.When they go bad it will set a code in the E-vap system.

    Sandy
     
  3. Texas Ton

    Texas Ton TS Member

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    Jan 29, 1998
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    Just to make sure, did you pull the fuel cap with it running?

    Make sure you have all codes written down, then (if you don't have a scanner) shut it off, remove the negative cable from the battery for a few minutes, relace and see if the code comes back.

    Check all hoses that are anywhere near heat, and make sure all are tight on fittings.
     
  4. maclellan1911

    maclellan1911 TS Member

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    valves are a big problem on toyota,vw and nissan. I have not seen many clogged canisters. Split hoses are another problem. If you have rot? rotted fuel necks and poor cap seal. see a lot of fords with small split/cracks at cap seat.

    Have had no luck with aftermarket caps.

    What type of car?
     
  5. TjayE

    TjayE Member

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    "Check fuel tank cap" light comes on. Will a new fuel tank cap remove this message from my instrument panel? My authorized GMC dealer told me I need a complete fuel tank venting system installed to the cost of $300.00 to $400.00. I am hoping that I only need a new cap. Tom E
     
  6. halfmile

    halfmile Well-Known Member

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    Location:
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    what a scam. I think a piece of electrical tape so you don't see the check engine light is a good Idea.

    I have had this code for 3 months now and it's getting to me.

    Where is the sensor located usually for this system? If I knew what the ECM wanted to see I would bypass the damn thing.

    HM
     
  7. Quack Shot

    Quack Shot Active Member

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    Halfmile,

    It usually isn't all that simple to bypass the Evap System Monitors. Many vehicles have a fuel tank pressure transducer and it will give different readings at different points in the diagnostic process. Yopu'd also need to defeat the comprehensive component monitor, which is designed to prove out sensors. A bypass would usually result in a failure being detected in the sensor. They have you coming and going. It's usually more work to bypass than it is to just fix it. You could always move to an area that does not mandate emissions inspections. I own three vehicles that are "inspected for life", as long as they stay registered as they currently are. That covers safety AND emissions. I don't expect that to last, since the politicians haven't gotten around to closing that loophole yet.
     
  8. halfmile

    halfmile Well-Known Member

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    Location:
    Green Bay Wisconsin
    Thanks for the info. We don't have emission testing.

    My gas cap seems ok although I don't know how to test it.

    I suppose I can plug away. I have heard so many horror stories about shops just replacing stuff till the problem goes away, If you're lucky it's only the 3rd or 4th thing for 3-400 bucks.

    Auto zone guys here will scan and sometimes have good tips. For obvious reasons they won't cancel a code though.

    My older Caddy was alot easier than this Buick. It would give you the code through the climate control panel, and you converted it from a list.

    Time to buy a restored 1956 model.

    HM
     
  9. birddog1964

    birddog1964 TS Member

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    90% of the time this code is set ether the gas cap is loose {when tightening the cap let it click 3 or 4 times to make sure it is tight} or the gas cap is bad. {The vent in the cap is bad}

    lee
     
  10. Irfner

    Irfner TS Member

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    Aug 28, 2006
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    This code sets in two trips. It is for the Vapor Pressure Sensor. Possible causes are the sensor, sensor plug or vacuum lines to the sensor. After repair do not clear the code. It will clear itself after a couple of drive cycles confirming the fix. If you are good with vacuum pumps and DVOMs there is a test procedure for it. Usualy a good visual inspection and or new sensor will fix it.
     
  11. maclellan1911

    maclellan1911 TS Member

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    there is also a preasure sensor valve under there, 2003 and in salt zones it can get pretty nasty under there. Alot of wire corrosion inside the insulation especially where the wire is bent. Some times the whole assembly is sold as a unit. Canister,vent valve, selenoids, preasure sensor and valve??
     
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