cookin1979

Everytime I take the gas cap off to fuel up, I get this tremendous sucking sound from my fuel tank. It makes no difference if the tank is empty or 3/4 full. What causes this? Is this normal? What's the advantages of a vented cap?
Thanks

thamzid

Sounds like the Vented Cap is no longer Venting. Make sure it is not plugged.

Brettmc

Do all caps need to be vented? The old gas cap on my 74 said "vented" on it (also had no gasket on it). The one I put on last night (from Zip) is unvented. Haven't had a chance to drive with the new cap on it. Is my gas tank going to implode??? :eek: :eek: :eek:

81Vette_by_eric

my beretta used to do that. mostly when i was running on fumes in summer. haven't heard it with the Vette yet. I agree with the need for a vented plug. I don't think the tank will implode, but it can't be good. I wonder, could that effect the fuel be pumped out by lowering the pumped pressure?

Brettmc

That's what I'm wondering, if a vacuum will form in the tank, eventually choking down the fuel pump.

Bobchad

Do you still have your vapor cannister and is the line running from the tank to it clear.