Sucking noise from filler cap
- rexthecat
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I bet it is just a rubber flap that has welded itself to the lid.
I'll have a look at mine if it ever stops raining here
If it suddenly breaks, go back to the last thing that you did before it broke and start looking there
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- helijohn
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facade wrote: There is a one way valve in the cap, that allows air into the tank, to prevent the tank sucking flat. It should prevent fuel coming out of the cap if the car falls over. I've never noticed mine hissing, but I don't stand next to the filler when it is running.
The fuel system is sealed, to prevent fumes reaching the atmosphere.
When it gets warm, and the fuel expands, it fills up the expansion space in the tank and there is a pressure valve in the small vent line that opens and allows vapour into the charcoal cannister next to the alternator.
The cannister is vented via a short rubber pipe to the air, and the charcoal holds the fuel vapour.
Next time the engine starts, air is drawn in through the charcoal cannister to the inlet manifold, purging all the vapour back to the engine.
If you overfill the tank, by shaking the car and filling right up the spout, on a hot day liquid fuel gets in the charcoal cannister, and this does cause a problem at the next start up when the cannister is purged.
The vapour control nicely explained!!
Those charcoal gizmos are expensive to replace and I think the whole system is OTT - paranoia.
Can't you take your cap apart?
There is a cap-in-bits thread I did somewhere on here.
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- idiotmobil
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