Help...81 c10 fuel leak

[81 zac]

Can anyone please give me some ideas why my fuel would leak out of the passenger side filler neck well it's running and I have my fuel tank selector switch set on the left hand side. Thanks in advance

 

[Charlie]

 

[Rusty Nail]

Anti-siphoning valve.

Did you know such a thing exists AND is equipped in your truck?

Seriously folks, if gas is coming out, your cap needs replaced. The '81 has a charcoal canister, is vented "directly" to the atmosphere through the gas cap I think..it's got that spring..
More information is necessary. Buy a new gas cap and report findings.

OR!
I reckon you could switch caps from the other side and see if the problem follows to isolate the cap.

That sounds pritty gud. I bet you need a new gas cap.

 

[81 zac]

Thank you for the help.