The Ignition Test Light is a handy tool to troubleshoot the Weber MPE-750 electrical system. You can determine if a power signal is being supplied to the fuel injector. This will help diagnose starting problems by informing you if there’s a problem within the ignition circuit.  Simply disconnect the fuel injector, and connect the wiring harness to the test light; it will “flash” if you have a pulse signal to the injector while attempting to start the engine.