BOSCH Electric Fuel Pumps: Operation
Pumps are activated by relays when ignition switch is in "START" or "RUN" position, and are protected from circuit overload by fuses and/or fuseable links. Fuel is circulated through pump rotor and brushes to discharge outlet. Pumps are a non-servicable component and should be replaced if not operating properly. Refer to appropriate Fuel Injection article in FUEL SYSTEMS Section for testing and diagnostic procedures .