There is no inertia switch in the MX-3. If your fuel pump has failed, you need to check for voltage at the pump first. If there is ground at the pump connector, and battery voltage when the engine is cranking, and the pump doesn't run, the pump is defective. You could run power and ground to the pump to be sure. If no power at the pump, then you need to go further. The pump is controlled by the ECM through a relay.