I'm on my third lift pump and I noticed today that my tank is sucking in on itself. I switched back to an Oem style while my new Holley is being warrantied. This all started when I noticed that I could pull my PF gauge down to 0psi, swapped in another pump and same deal. Can I really be sucking that much fuel through 7x12s? Like enough to suck my tank in on itself?

take the fuel cap off and see what happens.  Guessing your tank is not venting.

I second the above. Vent is plugged

^^^^^

Tank vent is a one way flapper valve mounted near the fuel lines at the tank top. It faces the dirt flying up and is about 3/16'' orifice or plastic tube. It sometimes clogs up. Best to get a vented fuel cap or make yours vented.

Thanks for the good description of where the vent is, JAG. I'll clean up there and see what it does for me.