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Hello. I have seen this topic of a 69 gas cap (vented) before but the answers seem to go both ways, or I'm just confused. The cap is vented but does that mean vapours come into the tank and out of the tank or is it just one way, into the tank? My vented cap allows vapours to go out and in, so do I have to replace? Thanks and take care.
The 1969 Corvette vented gas cap has check valve in the center of the cap. It is designed to release pressure from the tank at a predetermined value.That is what the rivet in the inside center bottom is for.
Your fuel tank ALWAYS needs some form of "vent". If you only have a fuel tank, the vent must be on the tank or in the cap. Otherwise, as you deplete fuel in the tank, it would collapse from the internal vacuum created by that fuel loss. For vehicles with a vapor collection canister, THAT system is the vent for the tank. But, it only works if the fuel cap is NON-vented.
So, is that clear or are you still confused about the "vented" tank issue?
Last edited by 7T1vette; Feb 26, 2021 at 12:10 AM.
Your fuel tank ALWAYS needs some form of "vent". If you only have a fuel tank, the vent must be on the tank or in the cap. Otherwise, as you deplete fuel in the tank, it would collapse from the internal vacuum created by that fuel loss. For vehicles with a vapor collection canister, THAT system is the vent for the tank. But, it only works if the fuel cap is NON-vented.
So, is that clear or are you still confused about the "vented" tank issue?
No, that explains very clearly. Thanks and take care.
69 Gas cap
