Sounds like a dud fuel pump to me. Check all the wires first . Funny though , 87 rx7 had no carburetor...it has electronic fuel injection.
Mazda didn't make the RX7 in 1974.
Inside the fuel tank
wat
18.5 gallons
in the tank
you will need a fuel pressure and flow gauge and then check actual meaured to specs.
first do a fuel pressure test also check fuel filter, fuel pressure regulator , injectors primary and secondary.look for external leaks specially the notorious fuel line under the intake manifold. and also if u have a good quality fuel.
The Mazda cx7 is not as good as the Rx7. The Rx7 has more power, better fuel efficiency and a sleeker appearance. The Cx7 is actually not as good as a Honda CR-7.
Check your main relay which is located under the dash near the fuse box.
Check the fuel filter for good flow of fuel. Next to check would be the fuel pump.
A fuel return line should flow freely back to the tank. There may be a check valve on the fuel return line that prevents backflow from the tank to the regulator.