I have an 85 GSL with under 55K miles on it. I had a weird experience yesterday. I had been driving for a while (making several stops). When I stopped at my final stop, I heard a buzzing. It was audible inside, but was much louder standing outside the vehicle. Especially when I crouched down by the rear wheels. This electronic buzzer continued to buzz even with the engine off, and the key removed. After a while, I discovered that there was a LOT of pressure built up in the gas tank. Is this just because I live in the desert, and the gas was sloshing around in the tank? Does anyone know if this is a common problem with the RX7? Could there be a plugged vent tube or something? Any ideas on how to solve this problem (vented gas cap, adding a vent hose and catch-can, etc.)? Be aware that yesterday was the first day it topped 100 degrees, here in Vegas. I don't know if that matters or not.

 

There's two pressure-relief valves in the -7: the tank vapor vent valve up at the engine (goes to your charcoal canister) and the overpressure function of the vent valve back at the fuel tank. You gas tank should never be able to develop more than about 1PSI of pressure if either of these is working right.