jeudi 21 août 2014

Fuel Overflow and Occasional P0456

Guten Tag, y'all!



I've been around BMW a bit, starting with an e28, to an e34, to e39 touring, and now I have an 04 330ci 6MT.



Fuel begins to overflow when I pump from empty to about half a tank. It's been difficult to pinpoint the leak--I get too embarrassed to look for it while at the pump, like I wet my pants or something.



So, first the symptoms:

1) the leak

2) occasional P0456 "Evaporative Emission Conrtol System Leak Detected (very small leak)"

3) gas odor remains pervasive even 24 hours later

4) occasional "check gas cap" light on dash

5) initially, it was occasional and might've only happened at the station i use the most. Now it seems to happen every time, no matter which pump/gas station I go to.



Attempts at diagnosis:

1) pulled purge vent valve

- valve opens when 12v is applied.

- momentarily holds 20-25in of vacuum. It's a consistent interval, about ten seconds every time.

2) removed wheel and fender cover

- looks like it might (maybe) be leaking from, or first collecting at and then leaking from, the point where the fill tube enters the tank



Questions:

1) is the purge valve behavior normal? should it hold vacuum indefinitely?

2) if the system was previously overfilled, could fuel have saturated the charcoal canister, inhibiting the passage of air and thus causing overflow? Might this also be why the odor is so persistant?



I'm thinking of going out to Strictly German this weekend, to pick up another canister and purge valve. If one of those proves to be the solution, I probably rebuild the original.



Thanks for any help you guys can offer.



**Edit** I've searched these forums for hours, and while I have found some info, nothing I've been able to locate on e46fanatics answers the questions above. The person with some of the most informative posts, jbeurotech, doesn't appear to be active anymore. I'm not the type of guy to go making a thread because he's too lazy/stupid to use the search function.




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