Gas Cap Leaking Under Acceleration

[Goose]

Hi Everyone,

Under hard acceleration, gas sloshes/leaks out from the cap on my 1971 Mustang, spills all over the road and my paint. Very embarrassing, but a bit funny as well! It has a typical twist on gas cap. Any thoughts? Am I missing a gasket?

Is this the one that I'm missing perhaps?

https://www.npdlink.com/store/products/mustang_gasket_tank_filler_to_panel-106709-2851.html

Thanks and hope you can help!

 

[Omie01]

That gasket doesn't seal the filler neck from the gas, its the gasket that seals the filler neck to the tail light panel. The gas cap should have a rubber gasket under the twist ears, with a little brass washer under it that provides the tension to seal the gasket against the filler neck mouth. Hope this helps.

 

[Kellogg]

This is the rubber gasket for the basic gas cap

https://www.npdlink.com/store/products/mustang_gas_filler_cap_gasket-106665-2850.html

For this type of gas cap

https://www.npdlink.com/store/products/mustang_gas_cap-106664-2850.html