DESCRIPTION
Bosch electric fuel pumps are 12-volt, positive displacement roller cell type. Operating pressure is determined by one or more external fuel pressure regulators in the engine compartment. Fuel pumps include an external replaceable discharge check valve, to prevent fuel from returning to the tank when pump is turned off. Some pumps may also incorporate a damper chamber on the outlet, to prevent pulsations in the fuel lines.
Scheme 50
OPERATION
Fuel pumps are actuated by relays when ignition switch is in "START" or "RUN" position, and are protected from circuit overload by fuses and/or fusible links. Fuel is circulated through pump rotor and brushes to the fuel outlet. Pumps are not serviceable and should be replaced when not operating properly. For fuel pump test procedures, see appropriate FUEL INJECTION article in this section.
REMOVAL
Remove sending unit access cover. Remove harness connector. Pull off supply line, return line and vent hose. Loosen retaining sleeve and pull out fuel gauge sendign unit. Pull off fuel hoses inside of sending unit housing. Detach electrical connections. Remove gravity valve.
Note. Do not allow smoking, open flame or sparks in area while servicing fuel system components. Disconnect battery ground terminal prior to removing pump.
INSTALLATION
To install reverse removal procedure.